- Cake:
- 2 cups baking mix
- 1 (10 ounce) package boysenberries
- 2/3 cup milk
- 1 egg
- 2 tablespoons brown sugar
- 1/2 teaspoon vanilla extract
- Streusel Topping:
- 1/3 cup baking mix
- 1/3 cup brown sugar
- 1 pinch ground cinnamon, or to taste
- 2 tablespoons butter, or to taste
- Preheat oven to 400 degrees F (200 degrees C). Grease a 9×11-inch baking pan.
- Mix 2 cups baking mix, boysenberries, milk, egg, 2 tablespoons brown sugar, and vanilla extract in a bowl until batter is moist, about 30 seconds. Pour batter into baking pan.
- Combine 1/3 cup baking mix, 1/3 cup brown sugar, and ground cinnamon in a bowl; cut in 2 tablespoons butter with a fork, until mixture resembles coarse crumbles. Sprinkle crumbles over the batter until covered.
- Bake in the preheated oven until a toothpick comes out clean, 20 to 25 minutes.