Adapted from Piece of Cake
What you need:
2 cups AP flour (you could totally do half wheat and half AP if you wanted)
1 Tlb baking powder
1/2 tsp salt
1 cup (2 sticks) margarine, softened
3/4 cup granulated sugar, divided
3/4 cup light brown sugar
1 Tlb vanilla
1 cup 2% milk (the original recipe called for whole so I tried 2% BUT after trying it, I think skim would work well too)
1 pint fresh blueberries, washed and dried (check for any stems)
1/2 tsp ground cinnamon
1. Preheat oven to 350 degrees. Spray a 9x13-inch baking pan with cooking spray and line it with a sheet of parchment paper with a few inches of overhang on two sides. Spray the parchment as well. (I clearly forgot this step so I am unsure of its crucial-ness BUT I am assuming it makes it easier to remove so give it a whirl and let me know if it helps!)
2. In a medium bowl, combine flour, baking powder, and salt. Set aside.
3. In your mixing bowl, beat margarine, 1/2 cup of granulated sugar and brown sugar until lightened in color and fluffy, about 2 minutes. Scrape down the sides and beat in the eggs one at a time. Add vanilla.
4. Add half the flour, mixing just until the flour begins to disappear. Add the milk and mix to incorporate. Add the rest of the flour and mix until there are a few streaks of flour left in the batter. Fold in the rest by hand until the batter is smooth.
5. Toss one cup of blueberries with 1 Tlb flour. Mix the floured berries into the batter and spread into the prepared pan. Sprinkle the remaining pint of blueberries on top of the batter.
6. Combine the remaining 1/4 cup of granulated sugar with the cinnamon and sprinkle evenly over the batter. Bake until a toothpick inserted comes out clean, about 45 minutes. Cool in the pan on a wire rack. Remove cake from pan (this would be easier if you had the parchment in the bottom) or cut into squares in pan.