These boozy mermaid beach cupcakes are a pirate’s temptation – brown sugar cupcakes filled with salted dulce de leche and topped with a salted rum dulce de leche buttercream. Oh, a gorgeous mermaid on the beach to lure you in. Those pirates won’t know what hit them!
✏️ Making a tasty and easy recipe
These salted rum dulce de leche cupcakes are so deliciously caramel sweet. The creamy buttercream with that spiced rum kick really tops it all off nicely.
My favourite part of this recipe is the buttercream. It’s beautifully thick like a caramel giving you a rich frosting but so full of that distinctive dulce de leche flavour.
When I first made these cupcakes, I used the salted rum dulce de leche sauce inside the cupcake. It was super tasty, but because it was a pourable sauce, it wasn’t quite thick enough and instead managed to seep its way into the brown sugar sponge. Still super tasty, but my cupcakes ended up with empty holes inside!
When I first made these, it happened to be one of the hottest days of the year. I had made the mermaid tails of white chocolate, set them in the fridge and then as soon as I popped them out of the moulds and onto the cupcakes, they wilted under their own weight and the fins fell off where they’d melted!
I live in the UK, so that kind of heat is definitely not expected. If you live in a hot country, you might need to refrigerate your pirate’s downfall cupcakes until ready to serve to prevent them from melting.
🥘 Ingredients notes
- As with many of my baking recipes, I recommend starting with room temperature ingredients. This will improve the consistency and ease at which your ingredients will mix together for a more delicious pirate’s temptation cupcake.
- Always sieve your flour, confectioners sugar and baking powder. I used to be a bit lazy and skip this part, but it really makes such a difference to get you smooth, lump-free mixtures.
- The quality of rum that you buy will have a big impact on flavour. I find the cheap rums are quite harsh and can lack some of the smooth spice of some of the other rums I’ve tried. Make sure to use your favourite spiced rum for a taste you’ll love. Or just a good brand of rum that you know people will love. I'm by no means a rum expert!
- When measuring your ingredients, I always recommend using weights rather than cups where possible for greater accuracy. Accuracy is especially important for the amount of flour used in your cupcakes.
🔪 Equipment notes
I like to use digital scales for weighing my ingredients as it's easier and more accurate than other scales. I'm a fan of these KitchenAid or Salter ones!
Use measuring spoons for your teaspoon and tablespoon amounts where possible. Be sure to level off the heaped ingredients in your scoops before adding them to your mix.
Once decorated and finished, it's best to place cupcakes into an airtight container. These brown sugar cupcakes should keep for several days in storage at room temperature.
If you want to freeze your cupcakes, you can wrap the unfrosted and undecorated cupcakes in plastic wrap / cling film and freeze them.
Your buttercream frosting can also be frozen in an airtight container. Both should keep for 1-2months in the freezer.
Defrost and use as normal per recipe. The buttercream may need to be beaten again to whip up to nice and fluffy before use.
💭 Top tips
- Don’t open the oven mid-bake. You’ll have probably heard this advice before, but it’s such an important factor that it bears repeating. I’ve been there before and nobody likes a cupcake with a sinkhole! I mean, you’re cutting one in anyway…
- When making your buttercream, make sure to use room temperature butter. Your butter should be soft enough to indent when you press it but not so soft you can squidge all the way in.
- For a gorgeously creamy buttercream, start by beating your butter until it’s light and fluffy. It could just be me, but this always seems to take longer than I think. It should be several minutes of beating the butter if using a stand/electric mixer. This will go a long way in giving you creamy and light frosting.
♻️ Alternatives and substitutions
In this recipe, you can either use dulce de leche from the shop or make your own using my simple recipe for dulce de leche (see my recipe for salted rum dulce de leche sauce).
If you’ve already made up a delicious jar of my salted rum dulce de leche sauce, then you can swap the dulce de leche, spiced rum and salt for the buttercream below, with 120g of the sauce. Add in an extra 1 tablespoon of spiced rum if you like the extra boozy kick.
I like to use a spiced rum for this recipe. The cinnamon and vanilla flavours complement the dulce de leche beautifully. You can switch it up though and use a dark rum, which will also be strong and full of flavour with an extra kick. You can also try using a white rum, which will be a lot more subtle in flavour.
Instead of using real rum in your pirate’s temptation cupcakes, you can swap this for rum extract, for an alcohol-free version. Swap the 4 tablespoon of rum in this recipe for 2 ½ teaspoon of rum extract. I also like to add an extra pinch of ground cinnamon and ½ teaspoon of vanilla if using rum extract so that you still get that spiced rum flavour.
Cupcake decorating ideas:
In the photos here I’ve made beach-themed mermaid design cupcakes - perfect for tempting any pirate with! To make your salted rum dulce de leche cupcakes the recipe for a pirate’s downfall, try the below:
How to fill a cupcake:
- I used a knife to cut a small hole in the centre of the cupcake. Take out this piece of cake and cut off the bottom part of the chunk, so you have a small piece of crust and a piece of excess sponge. Keep this small cut-off piece of excess sponge for crumbs for later to decorate. You can use a cupcake corer if you have one, but a knife works just as well.
- I then filled the cupcake hole with the salted dulce de leche and placed the cut cupcake top (the crust piece) back into the hole like a plug.
How to make a cupcake beach decoration:
- I used a round piping nozzle to pipe the buttercream across half the cupcakes.
- Crumble the excess pieces from the cupcake middles and press this into the buttercream you’ve piped to give a sandy beach effect.
How to make a cupcake sea waves decoration:
- Add a few drops of blue food colouring to your buttercream and mix to give you a sea coloured frosting. I then like to add a drop of green and another drop of blue and mix in, but not completely, to give a multi-toned effect. This should help your water look a bit more like the sea.
- I then used a flat petal piping tip to pipe the waves in a zigzag pattern across the other half of the cupcake top. Hold the flat piping nozzle vertically as you pipe.
How to make fondant seashells:
- Using a seashell silicone mould, you can press white fondant into the mould to give you small seashells to add to your beach.
- A top tip is to brush your silicone mould with icing sugar before pressing the fondant in. his will help you to get the fondant out easier afterwards.
- Another tip is not to overfill the mould with fondant, or you’ll end up needing to cut bits off once you remove it from the mould. You want the fondant to come to just below the sides of the mould.
- For an extra touch, you can brush pearlescent lustre dust across the shells to give them a little glittery shine. I like to use the sugarflair lustre dust.
- Alternatively, you can use white chocolate for your seashells by filling the mould with melted white chocolate instead and setting this in the fridge for 5mins.
Other decoration ideas:
Instead of using the pirate’s downfall beach theme for the cupcakes, you can opt for a simpler option of using a 1M piping tip to pipe big classic swirls onto your cupcakes. You can then drizzle some of the salted rum dulce de leche sauce on top for that extra decadence.
🧁 Other goodies
So, I definitely recommend that you whip up a batch of these pirate’s temptation cupcakes! But as an avid home baker, I’m sure you’re asking yourself “what next?”.
Well if you love tasty and easy cupcakes, then check out my recipe for easy Terry’s chocolate orange cupcakes. Or if you’re a fan of a boozy bake, then take a look at my Bailey’s Irish cream chocolate cheesecake or these salted caramel whisky cupcakes.
Looking forward to some new recipes? Check out my Facebook, Instagram and Pinterest pages for a few sneak peeks and some sweet inspiration!
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Boozy Mermaid Beach Cupcakes
Rate this recipe here:
- Mermaid tail mould
- Seashells mould
- Piping bag and piping tips - flat petal tip (for sea waves), small round tip (beach)
Brown sugar cupcakes:
- 170 g (¾ cups) unsalted butter (room temp.)
- 150 g (⅔ cups) light soft brown sugar
- 3 eggs
- 1 teaspoon vanilla extract
- 170 g (1⅓ cups) self-raising flour (or plain flour + 1 ½ teaspoon baking powder)
- 1 teaspoon baking powder
- 3 tablespoon milk
Salted rum dulce de leche buttercream:
- 200 g (1 cups) unsalted butter (room temp.)
- 400 g (3⅓ cups) icing sugar
- 4 tablespoon spiced rum
- 110 g (½ cups) dulce de leche (see notes)
- ½ teaspoon salt
Salted dulce de leche filling:
- 120 g (½ cups) dulce de leche (see notes)
- ½ teaspoon salt
Mermaid beach decorations:
- A few drops of blue food colouring
- A few drops of green food colouring
- 25 g (¼ cups) white fondant icing (for seashells)
- 100 g (¾ cups) white chocolate (for mermaid tails)
- Lustre dust in various colours (optional)
Brown sugar cupcakes:
- Preheat oven: 190°C / 170°C (fan) / Gas Mark 5 / 375°F
- For the sponge, cream together the butter and sugar, either using a spatula, electric hand mixer or stand mixer.
- In a separate bowl, beat the eggs until whisked up nice and fluffy.
- Add the eggs to the creamed butter and sugar and mix together.
- Stir in the vanilla extract and then sift in the flour, folding in gently until just combined.
- Add in the milk and stir until you have a smooth mixture.
- Divide the mixture evenly between the cupcake cases and bake for 15-20mins until risen and springy to the touch.
- Allow the cupcakes to cool on a wire rack while you make the buttercream.
Salted rum dulce de leche buttercream:
- Beat the butter (either by hand, using an electric mixer or stand mixer) until pale, light and fluffy. This could take several minutes.
- Sieve half of the icing sugar into the butter and beat until combined, then repeat this with the remaining half of icing sugar.
- Add in the dulce de leche, rum and salt (or the salted rum dulce de leche sauce and extra rum), mixing until smooth.
Dulce de leche cupcake filling:
- Mix together the dulce de leche and salt and in a bowl, stirring until smooth.
- Using a knife, cut a small but deep hole in the centre of the top of the cooled cupcake (roughly 1½ inch diameter), lifting out the chunk of cake you’ve just cut. This should go roughly halfway into the depth of the cupcake.
- Keep the chunk of cake removed, and cut off the bottom half of this. With this bottom sponge section, place this aside in a bowl for later.
- Spoon 2 teaspoon of salted dulce de leche into the hole you’ve created in the cupcake and then press the top half of the cake chunk back into the cupcake, sealing away the sauce inside the cupcake.
- Repeat this until each of your cupcakes have been filled with salted dulce de leche, keeping all of the sponge chunks for later.
Mermaid beach cupcake decoration:
- Separate half of the buttercream into a separate bowl, and add 2-3 drops of blue food colouring, stirring until smooth. You can then add an extra drop of blue and one of green and stir slightly to give a multitone effect.
- Add the un-coloured half of the buttercream to a piping bag with a round nozzle. Pipe this in smooth lines across half of each the cupcake in a single layer.
- Crumble the excess cupcake chunks from earlier into little crumbs, and press these into the buttercream halves of the cupcakes to look like sand.
- Add the blue frosting to a piping bag with a flat piping tip. Hold this so the line is vertical and pipe the blue icing in zigzags across the plain half of the cupcakes to look like waves.
- Take your seashell mould and brush icing sugar into the cavities then press your white fondant into the cavities before gently popping them out. Repeat until you have enough seashells for a couple per cupcake. Place these onto the sand side of your cupcake.
- Melt your white chocolate in the microwave, 30secs at a time, stirring between bouts until smooth.
- Pour you chocolate into the mermaid tail mould and set in the fridge for 10mins. Pop this out carefully, brush with lustre dust (optional) and top your cupcake with the tail. Repeat until you’ve topped as many cupcakes as you’d like.
- In this recipe, you can either use dulce de leche from the shop or make your own using my simple recipe for dulce de leche (see my recipe for salted rum dulce de leche sauce).
Nutritional information is an estimate based on an online nutritional calculator, actual values may vary.
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