In a medium saucepan melt and combine chocolate and butter. Let cool.
In a large bowl let egg whites stand at room temperature for 30 minutes.
Stir egg yolks and vanilla into the cooled chocolate mixture. Set
chocolate mixture aside. In a small bowl stir together the flour
and baking powder; set aside.
Preheat oven to 350 degrees. Beat egg whites with an electric
mixer on medium speed until soft peaks form. Add the sugar,
about 2 tablespoon at a time, beating on high speed about 2 minutes.
You're looking for stiff peaks. Stir softly about one-third of the egg
white mixture, flour mixture, and chocolate mixture all together.
Continue until all is blended. Spread into the 10oz round baking pan.
Bake 30 minutes. Cool cake completely. Loosen cake from sides of
pan and remove sides. Cut cake horizontally into two even layers, flip
bottom side up, layer with preserves, add next layer, and continue.
Top with Chocolate Ganache.