Cake Mix Doctor's Chocolate Velvet Cake From Chocolate from the Cake Mix Doctor, by Anne Byrn (with modifications)
Place a rack in the center of the oven and preheat the oven to 350°F (175°C). Generously grease two 9-inch round cake pans with solid vegetable shortening, then dust with flour. Shake out the excess flour. Set the pans aside.
Place the cake mix, buttermilk, melted margarine, cocoa powder, eggs, and vanilla in a large mixing bowl. Blend with an electric mixer on low speed for 1 minute. Stop the machine and scrape down the sides of the bowl with a rubber spatula. Increase the mixer speed to medium and beat 2 minutes more, scraping down the sides again if needed. The batter should look well combined. Divide the batter evenly between the prepared pans, smoothing it out with the spatula. Place the pans in the oven side by side.
Bake the cakes until they spring back when lightly pressed with your finger, 28 to 30 minutes. Remove the pans from the oven and place them on wire racks to cool for 10 minutes. Run a dinner knife around the edge of each layer and invert each onto a rack, then invert again onto another rack so that the cakes are right side up. Allow to cool completely, 30 minutes more.
Meanwhile, prepare the Cream Cheese Frosting.
Place one cake layer, right side up, on a serving platter. Spread the top with frosting. Place the second layer, right side up, on top of the first layer and frost the top and sides of the cake with clean, smooth strokes.
Store this cake, in a cake saver or under a glass dome, at room temperature for up to 3 days, or in the refrigerator for up to 1 week. Or freeze it, wrapped in aluminum foil or in a cake saver, for up to 6 months. Thaw the cake overnight in the refrigerator before serving.
Preparation Time: 8 minutes Baking Time: 28 to 30 minutes Assembly Time: 10 minutes