How to Make It
Preheat the oven to 350°. Butter two 8-inch round cake pans and line the bottoms with parchment or wax paper. Butter the paper and dust with flour, tapping out the excess. Sift the flour and cornstarch together twice. Melt the butter in a small saucepan; keep it warm.
In the bowl of a standing mixer, beat the eggs with the sugar and orange zest just until combined. Set the bowl over a saucepan of simmering water and whisk until the eggs are warm. Return the bowl to the standing mixer and beat the egg mixture at medium-high speed until pale and tripled in volume, 3 to 5 minutes.
Sift the flour mixture over the egg mixture in 3 batches, folding it in after each addition with a rubber spatula. Gradually pour the warm butter into the batter in a stream at the side of the bowl, folding it in until no streaks appear. Divide the batter between the pans and bake for about 20 minutes, or until the tops are light golden and the cakes spring back when lightly pressed. Let the cakes cool in the pans for 10 minutes, then run a thin blade around the sides and invert onto a wire rack to cool completely.
Using a sharp serrated knife, split each cake into 2 layers. Brush the cut sides with the Grand Marnier Syrup. Set 1 layer on a cake plate, cut side up, then spread it with a thin layer of the Grand Marnier Buttercream. Put 1 cup of the buttercream into a pastry bag fitted with a small round tip and pipe a buttercream border 1/2 inch thick around the edge of the cake layer. Scatter one-third of the raspberries inside the border. Spread the cut side of a second cake layer with a thin layer of the buttercream and set it frosted side down on the raspberries. Spread a thin layer of buttercream over the cake, then pipe a border all around. Repeat with the remaining raspberries, buttercream and cake layers. Spread the remaining buttercream around the sides and top and refrigerate until firm, about 3 hours or up to 2 days. Let the cake stand at room temperature for 30 minutes, then decorate with the sugar dots and daisies and satin ribbon before serving.