Created by Derf on April 28, 2013
Step 1: To prepare the pastry: sift the flour, cocoa and salt together into a bowl.
Step 2: Cut the butter into the flour mixture with a pastry blender or 2 knives until it resembles coarse meal.
Step 3: Add the sour cream and knead into a ball.
Step 4: Divide into 4 equal pieces and refrigerate 2 hours.
Step 5: On a floured board, roll each piece of dough out to a 10 x 10 inch square.
Step 6: Place each square on a buttered baking sheet, prick all over with a fork and bake in a 400f degree oven 10 minutes.
Step 7: Carefully transfer the pastry squares to wire racks to cool.
Step 8: They will be very fragile.
Step 9: To prepare the filling: Place the chocolate, cream and butter in a saucepan and stir over low heat until the chocolate and butter are melted.
Step 10: Beat the egg yolks until thick.
Step 11: Beat in a few tablespoons of the hot chocolate mixture and stir back into the hot chocolate.
Step 12: Stir in the vanilla and let the mixture cool to spreading consistency.
Step 13: Do not refrigerate or it will be too stiff to spread.
Step 14: Place 1 pastry layer on a serving plate and spread with the filling.
Step 15: Continue layering, leaving the nicest looking pastry square for the top.
Step 16: Sift powdered sugar over the top layer.
Step 17: Using a pastry bag fitted with a star tube, decorate the top layer with a little of the leftover filling.