- 1 cooking spray
- Cake:
- 2 cups white sugar
- 3/4 cup butter
- 3 eggs
- 2 teaspoons vanilla extract
- 4 cups all-purpose flour
- 1 cup milk
- 1 tablespoon baking powder
- 1 (10 ounce) jar boysenberry preserves (with whole berries)
- Streusel:
- 2 cups brown sugar
- 2 tablespoons brown sugar
- 1 1/3 cups all-purpose flour
- 1 cup butter
- Preheat oven to 350 degrees F (175 degrees C). Grease a 9×13-inch baking pan with cooking spray.
- Beat white sugar, 1 1/2 sticks butter, eggs, and vanilla extract in a bowl with electric mixer until fluffy. Add 4 cups flour, milk, and baking powder; mix until batter is thoroughly combined.
- Pour half the batter into baking pan. Spread half the boysenberry preserves over batter; pour the rest of the batter into pan and spread remaining preserves on top.
- Mix 2 cups plus 2 tablespoons brown sugar and 1 1/3 cup flour in a bowl; cut in 2 sticks butter with a fork until mixture resembles coarse crumbles. Sprinkle crumbles over the preserves until covered.
- Bake in the preheated oven until a toothpick inserted in the center comes out clean, 55 to 60 minutes. Cool before cutting.