- 1 (8-oz) package mascarpone, softened with 1 tbsp of cream
- 1/4 cup powdered sugar
- 2 teaspoons orange zest
For cake: Grease and flour the bottom(s) of two 9x2-inch pans or one 9-inch springform pan; line with wax or parchment paper. Sift together cake flour and 1/4 cup sugar twice; set aside. Melt butter in a small saucepan; off the heat and let sit for 4 minutes. Once cooled, remove the film from the top; carefully pour into a heatproof bowl, leaving the solids behind - set aside.
Whisk the eggs and 3/4 cup sugar in a large heatproof bowl; set over a pot of barely simmering water - whisk constantly until the mixture is warm to the touch (about 110 degrees F). Remove the bowl from the heat and beat on high speed until the mixture is lemony-colored, has tripled in volume. - like a continuous flat ribbon when dropped from a spoon (5 minutes in a heavy-duty mixer with the whisk attachment, 10 - 15 minutes with a hand-held mixer).
In 3 additions, sift the flour mixture over the top and fold in very gently with a rubber spatula. If the butter has become to solid, reheat briefly and transfer to a medium bowl. Fold about 1 1/2 cups of the egg mixture into the butter until completely incorporated, along with the vanilla extract. Bake until the cake begins to pull away from the sides of the pan(s) and the top springs back when lightly pressed, about 15 minutes in cake pans, 30 minutes in a springform pan. Let cool in the pan(s) on a rack for 10 minutes. Slide a thin knife around the cake to detach it from the pan(s); remove the side of the springform pan, if using. Invert the cake and remove the paper liner(s). Let cool right side up on the rack.
For berries: While the cake is baking, place the berries in a glass bowl and pour Grand Marnier on top. Allow 30 to 40 minutes for the berries to macerate and thaw.
For the mascarpone whipped cream: whip the heavy cream in a large metal bowl, then (using the same hand mixer), whip the mascarpone, sugar and orange zest into a smaller separate bowl. Fold mascarpone into the whipped cream.
Slice the cake into 3 layers. spoon berries with juice between cakes layers, then spread over whipped cream. Decorate top with mascarpone whipped cream.