Heat oven to 350°F. Coat two 9-inch round cake pans with nonstick cooking spray. Line bottoms with waxed paper; coat paper.
In large bowl, combine cake mix, 1-1/2 cups water, egg whites, oil and almond extract. Beat on medium speed for 2 minutes, scraping down sides. Beat in melted white chocolate. Stir in almonds. Divide batter into pans, spreading evenly.
Bake at 350°F for 30 to 35 minutes or until toothpick comes out clean. Cool on wire racks 10 minutes. Invert cake layers onto racks; remove waxed paper. Cool completely.
Meanwhile, bring cream to a boil in saucepan. Stir in espresso powder to dissolve. Stir in liqueur, if using. Place semisweet chocolate in medium-size bowl. Pour hot cream over top; let stand 1 minute. Stir until smooth. Cover; refrigerate frosting 45 minutes, until good spreading consistency.
To assemble, place 1 cake layer on cake stand; tuck waxed-paper strips under edges. Spread with 1/2 cup preserves. Place second layer on top. Melt remaining preserves; brush on top and sides of cake. Spread frosting over top and sides. Refrigerate at least 1 hour or overnight. Garnish with sliced almonds, if desired.