To prepare a thousand layer chocolate brioche recipe, you first need to prepare the filling for the cake. To do this, first you'll need the following ingredients: 1 pound of unsalted butter 1 cup of confectioners' sugar 1 tablespoon of vanilla extract 1 teaspoon of salt 2 tablespoons of milk Instructions: Preheat the oven to 350 degrees F (180 degrees C). Grease and flour two 8-inch round cake pans. Line the bottom and sides of each pan with parchment paper. Set aside. In the bowl of an electric mixer, cream the butter with the sugar until light and fluffy. Add the egg and vanilla and beat on medium speed until the mixture reaches stiff peaks. Gradually add the flour mixture, beating after each addition until just combined. Pour the batter into the prepared pan and bake for 30 to 35 minutes or until puffed and golden brown. Allow to cool before removing from the pan. Serve warm or at room temperature.