Grease and base line two 20 cm (8 in) sandwich tins. Preheat oven to 160 °C fan, 180 °C conventional, gas mark 6.

For the cake: Sift together the flour, cocoa and baking powder. In a separate bowl, beat together baking spread and sugar until pale and fluffy. Add the eggs, a little at a time, whisking well and then fold in the sifted ingredients. Finally, gently stir in the Crunchie Bits.

Divide the mixture between the two tins and level the surface. Bake for about 25 minutes or until springy to the touch. Loosen the edges with a palette knife, and leave to cool in the tins for a few minutes before turning out onto a cooling rack.

For the icing: Whilst the cake is cooling make the icing. Put the butter into a bowl and beat well then gradually beat in the icing sugar, followed by the dulce de leche. Use half the icing to sandwich the cakes together and the remaining half to decorate the top. Scatter the remaining.