Blueberry Buttermilk Coffee Cake in 45 Min

Instructions:

1. Preheat your oven to 350°F (175°C). Grease a 9x9 inch pan with butter or line it with parchment paper.
2. In a small bowl, toss the blueberries with 1 tablespoon of the measured flour from the cake ingredients until lightly coated.
3. Whisk together the streusel flour, brown sugar, and cinnamon. Use a fork or pastry cutter to work the cold cubed butter into the mixture until it resembles coarse, pea-sized crumbs; set aside in the fridge.
4. Beat the softened butter and granulated sugar on medium-high until pale and fluffy (about 3 minutes).
5. Beat in the egg and vanilla extract until fully incorporated and smooth.
6. In a separate bowl, whisk the remaining flour, baking powder, and salt.
7. Add half of the dry ingredients to the butter mixture, stir on low, then pour in the buttermilk, and finish with the remaining dry ingredients. Mix only until just combined.
8. Gently fold in the flour-dusted blueberries using a spatula.
9. Spread the batter into the prepared pan and sprinkle the cinnamon streusel evenly over the top.
10. Bake for 35 minutes or until a toothpick inserted into the center comes out clean.