I use the Trader Joe's Multigrain Baking & Pancake Mix. The side of it has a recipe for a blueberry coffee cake and this was my version. Also, I don't keep buttermilk around but instead use dry buttermilk that I keep in the fridge and mix it with water according to the directions.
This is really yummy served warm with a tiny bit of whipped cream on top.
1 c. buttermilk
3 T. oil
2 1/2 c. baking mix
1/2 c. sugar
1 1/2 c. fresh raspberries
In a large bowl, whisk together egg, buttermilk, and oil.
Stir in baking mix and sugar just until moistened.
Fold in berries.
Spread batter into an 8x8 square pan coated with cooking spray.
Bake 45-50 minutes at 350 or until top is golden brown and a wooden toothpick in center comes out clean.
Let cool in pan 10 minutes. Serve warm.