Add a taste of summer to any occasion with these berry-sweetened cakes. Using frozen berries allows you to enjoy this easy-to make treat year round. The surprise filling will delight any crowd!
Preheat oven to 350°F. Spray pans with vegetable pan spray. Place pans on cookie sheet.
For cake, drain strawberries; reserve liquid. Add enough water to reserved berry liquid to make 1-1/3 cups. Finely chop berries. In large bowl, beat cake mix, berry liquid, egg whites and oil with electric mixer at medium speed 2 minutes. Fold in chopped berries. Divide batter evenly among prepared pans (about 1/2 cup per pan). Bake 18-20 minutes or until toothpick inserted in center comes out clean and cakes are golden brown. Allow cakes to cool in pans on cooling rack for 10 minutes. Remove from pans; cool completely. Repeat with remaining batter.
Meanwhile, prepare filling. Drain strawberries and chop, reserving liquid. Add enough water to liquid to equal 1-1/4 cups. In large saucepan, combine strawberry liquid, sugar and lemon juice; heat, stirring occasionally. Stir together cornstarch and 1-1/2 tablespoons cold water. Stir into hot strawberry mixture; heat until mixture boils and thickens. Transfer to medium bowl; cool to room temperature; fold in strawberries and refrigerate until ready to use.
To prepare icing, combine buttercream and jam with electric mixer until smooth.
Spoon filling into cooled cake cavities. Assemble cakes by inverting one layer onto second layer. Spatula ice cakes. Keep refrigerated until ready to serve.
Makes 5 cakes.