Preheat oven to 350 degrees F. Lightly grease two 8x2-inch round cake pans. Line bottom of pans with parchment paper. Lightly grease the paper. Flour pans, shaking out excess; set aside.
In a medium bowl, whisk together the flour, cocoa, and salt. Set aside.
In a stand mixer fitted with a paddle attachment, combine the butter, sugar, and oil. Beat until light and fluffy. Add the eggs one at a time, beating well after each addition. Beat in the food coloring on low speed (mixture may look curdled).
Alternately add flour mixture and buttermilk, beating on low after each addition just until combined. Add the vanilla .
In a glass measuring cup, dissolve the baking soda in the vinegar. Add to the batter; beat on low just until combined.
Pour batter into prepared pans.Bake for 35 to 40 minutes or until a wooden pick inserted in the middle comes out with a few moist crumbs. Cool cakes on a wire rack for 10 minutes. Remove cakes from pans. Let cool.
When cakes are fully cooled, wrap in plastic wrap and refrigerate for at least 2 hours. Before frosting, with a long serrated knife, cut each cake in half horizontally. Place one half on a serving plate. Frost top with about 1 cup of frosting. Repeat with remaining cake halves and frosting. Arrange fresh berries around cake. Refrigerate to store.
Whipped Cream Cheese Frosting
In a medium bowl, using an electric mixer on medium speed, beat the cream to nearly stiff peaks; set aside. In a separate large bowl, using an electric mixer on medium speed, beat the cream cheese, powdered sugar, and vanilla until smooth and fluffy. Add the whipped cream to the cream cheese mixture and beat quickly to combine.