Melt the chocolate in a water bath. Add the softened butter and stir until smooth.
Combine the sugar with the almond meal in a bowl then add the eggs one by one and stir well after each egg.
Line a pie dish with one of the puff pastry sheets. Add the almond meal mixture then pour over the chocolate mixture. Cover with the second puff pastry sheet. Seal the edges of the dough with warm water if necessary.
Brush the cake with the egg yolk. With a knife score the pastry in a criss-cross pattern being careful not to make any holes in the dough.