Preheat the oven to 190°C/170°C fan/gas mark 5/375°F.

Line the muffin tin with 10 paper cases.

Beat the cake ingredients together thoroughly (butter, caster sugar, eggs, cocoa, flour, baking powder, salt, vanilla extract).

Divide the mixture between the paper cases.

Cook for 15-20 minutes until the cake surface springs back when touched lightly.

Leave in the tin for 5 minutes, then remove and leave to cool on a wire rack.

Sieve the jam if using.

Beat the softened butter and jam with an electric hand mixer. Gradually add the icing sugar, beating well.

Add 2 drops of colouring and mix in well. Adjust colouring as needed for desired shade.

Cut the tops off the cakes using a sharp knife, creating a cone-shaped hole.

Trim the lid to flatten it and cut a heart shape out from the underside.

Pipe a swirl of buttercream into the cake and position the heart shape onto the cake.