1. Heat oven to 350 degrees. Butter an 11 1/2-by-9 1/4-by-2 1/2-inch heart-shaped cake pan and line with parchment paper. Butter and flour the parchment paper, and set aside.

2. Set the bowl of an electric mixer over, but not touching, a pot of simmering water. Combine the granulated sugar and eggs in the bowl, and whisk until mixture is warm to the touch, about 2 minutes.

3. Transfer the bowl to an electric mixer fitted with a whisk attachment, and beat on high speed until the mixture is very thick and pale, about 4 minutes. With a rubber spatula, gently transfer the mixture to a large mixing bowl. Sift in the flour in three additions, folding gently after each. Combine the butter and the vanilla, and add in a steady stream as you fold in the third addition of flour. Fold gently, and transfer to prepared pan. Smooth the top with an offset spatula.

4. Bake until the cake is springy to the touch and golden brown, about 40 minutes. Transfer to a wire rack to cool completely. When ready to use, turn out cake onto a cutting board or a cake turntable covered with parchment paper, and carefully peel the parchment paper off the cake.

5. To assemble: Using a serrated knife, cut cake in half horizontally. Brush cut sides of cake liberally with simple syrup. Spread bottom layer to within 1/2 inch of edge with half of the whipped cream. Cover cream with an even layer of raspberries. Spread remaining whipped cream over berries. Place top of cake cut side down over cream. Dust with confectioners' sugar and cocoa powder, if desired.