Heat your oven to 350 degrees. Coat a 13 x 9-inch cake pan with nonstick spray. Line the bottom of the pan with wax paper & then coat the paper with additional cooking spray. Prepare the cake mix according to the box directions with the eggs, oil & water. Bake for 35 minutes, or based on recommended time on box, or until the cake springs back when pressed.

Allow to cool for 10 minutes on a wire rack before removing from the pan and allowing to cool completely.

While the cake cools, in a large metal bowl, combine the egg yolks, 1/2 cup sugar, 1/2 cup water & the butter. Create a double boiler by placing the bowl over a pot of simmering water. Cook, whisking constantly, for about 7 minutes, or until the mixture is thickened & has reached a temperature of 160 degrees. Remove the bowl from over the saucepan & whisk in the chopped chocolate until smooth.

In a separate bowl, beat 1 cup of cream with 2 tablespoons of sugar and the vanilla until medium-firm peaks form. Gently fold the whipped cream into the chocolate mixture until no white remains. Cover the surface directly with plastic wrap & refrigerate for at least 1 hour.

Once the cake has cooled, cut into 1 & 1/2 inch cubes. Whip the remaining heavy cream with the remaining 3 tablespoons sugar until peaks are formed just as before. Begin layering the trifle: Spoon half the cake cubes into a 4 quart glass serving dish; slightly compress. Spread half of the chocolate mousse over the cake cubes. Top the mousse with 1 package of the fresh raspberries & then half of the whipped cream. Repeat the layers until the serving dish is full.

Garnish with chocolate curls (optional). Serve immediately or keep refrigerated until ready to serve - up to overnight.