cups all-purpose flour
teaspoons baking powder
cup vegetable oil
teaspoon cream of tartar
cup strawberry jam
cups sliced fresh strawberries, raspberries, blackberries, and/or blueberries, stemmed and halved
cup whole fresh strawberries, raspberries, blackberries, and/or blueberries
1. Preheat oven to 350°F. Grease bottoms of two 8x1 1/2-inch round cake pans. Line bottoms with parchment paper or waxed paper; grease and lightly flour pans. Set pans aside. 2. In a large bowl stir together flour, cornstarch, baking powder, and salt. Add the water, oil, milk, and vanilla. Beat with a wire whisk until smooth. 3. In a medium bowl combine egg whites and cream of tartar. Beat with an electric mixer on medium speed until soft peaks form (tips curl). Gradually add sugar, beating on high speed until stiff peaks form (tips stand straight). Fold beaten egg whites into batter. Pour batter into prepared pans, spreading evenly. 4. Bake for 22 to 25 minutes or until a toothpick inserted near centers comes out clean. Cool in pans on wire racks for 10 minutes. Remove from pans; cool completely on racks. 5. To assemble, use a long serrated knife to cut cake layers in half horizontally. Place one cake layer, cut side down, on a serving plate. Spread with a generous 3/4 cup of the Butter Frosting and 1/4 cup of the jam. Top with 1 cup of the sliced berries. Repeat with two more cake layers. 6. For top layer, place final cake layer cut side down and spread with 3/4 cup Butter Frosting, 1/4 cup jam, and top with 1 cup whole berries. Butter Frosting: In a medium bowl beat 1/2 cup softened butter with an electric mixer on medium to high speed for 30 seconds. Gradually add 3 cups powdered sugar, beating well. Beat in 3 tablespoons milk and 2 teaspoons vanilla bean paste or vanilla. Gradually beat in 3 cups additional powdered sugar. If necessary, beat in additional milk, 1 teaspoon at a time, to make of spreading consistency.