Heat oven to 350°F. Grease and flour one (9-inch) round and one (9-inch) square baking pan. Set aside.
Stir together flour, baking powder and salt in bowl. Set aside.
Beat sugar and butter in bowl at medium speed, scraping bowl occasionally, until creamy. Add 1 egg white at a time, beating well after each addition. Add almond extract. Add flour mixture alternately with milk, beating at low speed after each addition just until mixed.
Place 2 1/2 cups batter into prepared round pan; place remaining batter into prepared square pan. Bake 29-34 minutes or until toothpick inserted near center comes out clean. Cool 10 minutes on cooling rack. Loosen cakes by running knife around inside edge of pans. Carefully remove cakes from pans; cool completely.
Combine all filling ingredients in saucepan. Cook over medium heat, stirring constantly, 5-7 minutes or until mixture comes to a boil. Boil 1 minute; remove from heat. Refrigerate 30 minutes or until cool.
Place 1/2 cup milk and 6 ounces white chocolate in another saucepan. Cook over low heat, stirring occasionally, 7-8 minutes or until chocolate is melted. Cool 30 minutes.
Combine cooled chocolate mixture, powdered sugar and 1/2 cup butter in bowl. Beat at medium speed, scraping bowl often, until creamy.
Cut cakes horizontally in half into layers using serrated knife. Cut round cake vertically in half.
Place bottom of square cake layer onto serving plate or tray; place bottom halves of round layer on two adjacent sides of square layer, forming a heart. Spread with filling. Place top half of each cake layer on filling. Frost top and sides of cake with frosting. Garnish with chocolate curls, if desired.