Combine chocolate squares and butter in a heavy saucepan, cook over low heat until melted, stirring often.
Remove from heat, and stir in flour.
Add egg yolks, one at a time, stirring well after each addition, set aside.
Beat egg whites (at room temperature) until foamy, gradually add sugar, 1 tablespoon at a time, beating until stiff peaks form and sugar dissolves.
Fold egg whites into chocolate mixture.
Pour into 3 greased and floured 8-inch round cakepans, bake at 350° for 20 to 25 minutes or until a wooden pick inserted in center comes out clean.
Cool in pans 10 minutes (layers settle as they cool).
Remove layers from pans; cool on wire racks.
Spread 1/3 cup raspberry preserves between each layer, drizzle chocolate glaze on top.