Once the cakes have cooled completely, melt the chocolate either slowly in the microwave or a bain marie.
Place the chocolate to one side and allow to cool slightly but make sure it stays pourable.
In the meantime, beat the butter, cocoa powder and icing sugar together.
Pour in the melted chocolate and continue to beat.
Finally pour in the cream and whisk until the buttercream is soft and spreadable.
Pipe circles of buttercream over the bottom layer of the cake.
Drain the strawberries and layer over the buttercream.
Pipe more buttercream over the strabwerries and place the second layer of the cake on top.
Finally, pip circles around the outside of the top layer.
Using a small spatula drag the centre of the piped circle towards the centre of the cake.
Pipe another ring of buttercream slightly inside the first, again use a spatula to drag the buttercream towards the centre.
Repeat until the whole cake is covered.
Pipe a small mound of buttercream in the centre then top with the prosecco truffles.