Prepare the cake in four 8-or 9-inch round pans. Cool thoroughly. Set aside one layer for another purpose. Split the three layers in half (working around the layer with a bread knife and inching toward the center, or with a thread wrapped around the layer and worked back and forth as you tighten it).
Meanwhile, prepare the buttercream: In a medium saucepan, combine the granulated sugar and water over medium heat, stirring until the sugar is dissolved. Continue to cook without stirring until the mixture reaches 240 to 250 degrees -- the soft-to firm-ball stage.
In the large bowl of an electric mixer, slowly add the syrup to the egg yolks, beating all the while and occasionally scraping the side of the bowl. When the syrup and eggs are well blended, set them aside to cool to room temperature.
When the syrup mixture is cool, beat in the soft butter, a piece or two at a time. Then beat in the powdered sugar, orange extract, orange zest and vanilla. Whip the mixture at medium speed for about 1 minute. Chill about 20 minutes, until it has thickened, then whip until it is very stiff (if you don't whip it enough, it won't have as much volume as it should).
Assemble the cake: Put the bottom half of one layer on a cake plate, cut side up, and spread about 1/2 cup of the raspberry preserves completely across it. Top with the top of that layer, cut side down (and with any hump in the middle sliced off), and spread with about 3/4 cup of frosting. Repeat with next two layers and the bottom of the third layer and its layer of preserves. Add top layer. Coat sides with a thin layer of frosting, just to cover gaps and hold crumbs in place. Frost top completely, then sides; decorate top with remaining frosting. Refrigerate until serving time.
Nutrition information per serving:
