Pre-heat oven: 190°C / 170°C (fan) / Gas Mark 5 / 375°F
Cream the butter until soft, then add the remaining cookie ingredients and mix until a smooth and thick dough forms.
Line a baking tray with parchment or a baking mat and add the dough to a piping bag (no tip) or fill a sandwich/freezer bag with the corner cut off (roughly an inch wide).
Pipe a “v” shape with the dough, a few inches long. Making one dash at a time, starting each line at the top and meeting them together at the bottom of the v.
Repeat the above step, piping as many “v” shapes as possible and leaving a few inches gap between each.
Bake for 7-10mins until lightly golden at the edges then allow the biscuits to cool on a wire rack while you prepare the filling.
While the cookies cool, beat the butter until smooth and fluffy, using a spatula or electric mixer. Slowly add in the icing sugar, stirring until smooth.
Microwave the jam for 10 secs then stir until you get a smooth liquid. Allow this to cool for a few minutes to room temperature, then stir this into your buttercream, beating together until fully combined.
Once the cookies have cooled, using a teaspoon or piping bag and star tip, cover the flat underside of one cookie with buttercream and lightly press the flat side of another on top, creating a sandwich.
Repeat until all of the cookies have been filled and sandwiched, then lightly dust with icing sugar and enjoy.