- Preheat oven to 350°F.
- Butter and flour two 9-inch-diameter cake pans with 1 1/2-inch-high sides.
- Sift sifted flour, cocoa powder, baking powder, baking soda, and salt into medium bowl.
- Whisk buttermilk, food coloring, vinegar, and vanilla in small bowl to blend.
- Using electric mixer, beat sugar and butter in large bowl until well blended.
- Add eggs 1 at a time, beating until well blended after each addition.
- Beat in dry ingredients in 4 additions alternately with buttermilk mixture in 3 additions.
- Divide batter between prepared pans.
- Bake cakes until tester inserted into center comes out clean, about 27 minutes.
- Cool in pans on racks 10 minutes.
- Turn cakes out onto racks; cool completely.
- Beat cream cheese and butter in large bowl until smooth.
- Beat in vanilla.
- Add powdered sugar and beat until smooth.
- Place 1 cake layer, flat side up, on platter.
- Spread 1 cup frosting over top of cake.
- Arrange 1 basket raspberries and 1/2 basket blueberries atop frosting, pressing lightly to adhere.
- Top with second cake layer, flat side down.
- Spread remaining frosting over top and sides of cake.
- Arrange remaining berries decoratively over top of cake. Can be made 1 day ahead.
- Cover and refrigerate.
- Let stand at room temperature 1 hour before serving.
- People who made this cake have made the following amendments: Went with the recommendation of increasing the following ingredients: 4 tbsp cocoa, 3 tbsp red food coloring, 1 tbsp vanilla, 1/4 cup veg. oil (in addition to existing butter), 1 1/3 cup buttermilk