25g caramel flavoured chocolate , finely chopped (we used Lindt)
Heat oven to 180C/160C fan/gas 4. Lightly grease 2 x 23cm loose-bottom cake tins and line with a circle of baking parchment. Beat together the butter and sugar until pale and creamy. Add the eggs, one at a time, beating well between each addition, then add the baking powder, cocoa and a third of the flour. Mix well to combine, then stir in half the soured cream. Alternating between adding the flour and soured cream, mix everything until just combined. Spoon into the prepared tins, then smooth over the surface with a spoon.
Bake for 30 mins or until the cakes are firm to touch and a skewer inserted into the centres comes out clean. Leave to cool in the tins for 5 mins, then turn out onto a rack and cool completely.
When you're ready to serve, whip the double cream with 2 tbsp Dulce de leche until soft peaks form. Place 1 cake on a serving plate and spread with half the cream, then drizzle over the remaining Dulce de leche. Top with the other cake, then spread the remaining cream on top. Sprinkle with the chocolate. Chill until ready to serve.