Blueberry Blue Velvet Cake

1. Preheat the oven to 350 degrees. Butter and flour two 9-inch cake pans and line each pan with a round of parchment paper.
2. In a medium bowl, whisk together the flour, cocoa powder, baking soda and salt.
3. In a large bowl (or stand mixer fitted with the paddle), cream the butter, sugar and oil until light and fluffy. Add the eggs, one at a time, scraping down the sides of the bowl and beat until incorporated. Beat in the vanilla, vinegar and food coloring.
4. Add the flour mixture to the batter in 3 batches alternating with the buttermilk, mixing well after each addition. Fold in the blueberries.
5. Divide the batter evenly between the prepared pans and bake for 30 to 40 minutes or until a toothpick inserted into the center comes out with a few moist crumbs. Cool on a baking rack for 15 minutes before removing the cake from the pans. Let cool completely before frosting.
6. While the cake cools, prepare the frosting. In a standing mixer fitted with the paddle attachment, or with a hand-held electric mixer in a large bowl, mix the cream cheese, butter and preserves until blended. Add the sugar and mix on low speed until incorporated. Add the vanilla and blue food coloring (if using). Increase the speed to high, and mix until light and fluffy, about 5 minutes. Add more powdered sugar to reach desired consistency. Store in the refrigerator until somewhat stiff, before using. (May be stored in the refrigerator for 3 days.)
7. Slice each cake into 2 layers and frost, stacking the layers. Top with additional blueberries.

Source: Adapted from my Gluten-Free Green Velvet Cake.