To sour milk: use 1 tablespoon vinegar plus milk to equal 1 cup.
Beat egg whites in small mixer bowl until foamy; gradually beat in 1/2 cup sugar until stiff peaks form. Set aside. Combine flour, 1 cup sugar, cocoa, baking soda and salt in large mixer bowl. Add oil, buttermilk or sour milk and egg yolks; beat until smooth. Gently fold egg whites into batter.
Grease and flour 2 heart-shaped cake pans or 9-inch layer pans; pour about 1 2/3 cups batter into each pan. (Reserve remaining batter in refrigerator while first 2 layers bake.) Bake at 350 degrees for 18-20 minutes or until cake springs back when lightly touched in center. Cool 5 minutes; invert onto wire rack. Bake remaining layer; cool completely.
Prepare Cream Filling. Place 1 layer on serving plate; pipe or spoon 1-inch edge 1/2-inch thick around layer; spread 1/2 cherry filling in center. Top with second layer. Spread with 1/2 remaining Cream Filling.
Top with third layer. Spoon remaining cherry filling onto top of cake, leaving 1-inch edge. Prepare Chocolate Whipped Cream. Frost sides of cake with Chocolate Whipped Cream. Pipe top edge with remaining Cream Filling. Chill completely; store in refrigerator until serving.
Whip 1 cup heavy cream with 2 tablespoons sugar and 1 teaspoon vanilla in small mixer bowl until stiff peaks form.
Combine 1/2 cup sugar and 1/4 cup unsweetened cocoa in small bowl. Add 1 cup heavy cream and 1 teaspoon vanilla; beat on low speed to combine. Beat on medium speed until stiff peaks form. Serves a group.
