Blueberry Coffee Cake

Preheat the oven to 350℉ (175 ℃). Grease a 9×9in pan and line it with parchment paper.
Add 2 1/4 cups (382 g) of the blueberries to a medium bowl. Toss them with 1 tbsp (8 g) of flour. Set aside for later.
(The remaining 3/4 cup/128g will be used for topping the coffee cake with.)
3 cups (510 g) fresh blueberries
To a large bowl add the larger portion of butter, granulated white sugar and the larger portion of brown sugar. Cream together with an electric mixer.
3/4 cup (168 g) unsalted butter, softened, 1 cup (200 g) granulated white sugar, 1 cup (220 g) light brown sugar, packed
Add in the flour and salt and mix on low speed until combined. It should resemble little crumbs.
3 cups (375 g) all-purpose flour, spooned and leveled, 3/4 tsp salt
From this mixture, remove 3/4 cup (125 g) of it and add it to a small bowl.
To the smaller mixture, add in the smaller portion of butter, smaller portion of brown sugar and cinnamon. Mix until combined. It should resemble large clumps. Set aside the streusel.
2 tbsp (28 g) unsalted butter, softened, 1/2 cup (110 g) light brown sugar, packed, 2 tsp cinnamon
Add the baking soda to the buttermilk and mix until it is dissolved. The baking soda will cause the buttermilk to expand, so make sure you are using a big enough liquid measuring cup to account for this.
1 tsp baking soda, 1 cup (240 ml) buttermilk, at room temperature
To the larger mixture, add in the buttermilk mixture, the egg and vanilla. Mix on medium speed until combined.
1 egg, at room temperature, 1 tbsp vanilla
Add in the larger portion of blueberries and gently fold them into the batter with a rubber spatula.
Pour the batter into the prepared pan and spread it evenly with spatula.
Sprinkle the remaining 3/4 cup (128 g) of blueberries on top. Then sprinkle on the streusel.
Bake the coffee cake for 70-80 minutes, or until a toothpick comes out clean from the center.
Let the coffee cake cool in the pan on a wire rack for 30 minutes, then pull up on the parchment paper to release it from the pan. Let the coffee cake continue cooling on the cooling rack until completely cooled.
When the coffee cake is cooled, mix together the powdered sugar and milk in a small bowl. Start with 3 tsp of milk and add more as necessary. You'll want it to to be a pourable consistency without being too runny.
1 cup (130 g) powdered sugar, 3-5 tsp whole milk
Drizzle the icing over the coffee cake and cut it into 16 slices. Then enjoy :)

Ingredients

Instructions