A blueberry coffee cake recipe based on America's Test Kitchen's version of the Renny Powell's Pillsbury Recipe & Baking Contest recipe from 1954.
283grams(or 2 cups) unbleached all-purpose flour
227grams(or 2 sticks) unsalted butter, softened
100grams(1/2 cup minus 1 tbsp) granulated white sugar
130grams(1/3 cup) light or golden brown sugar
1/2cup1% milk (or any milk available)
1/2teaspoonpure vanilla extract
135 grams(or 1 cup) frozen wild blueberries (divided—half in batter, half in topping)
1teaspoonunbleached all purpose flour
35grams(or 1/8 cup) granulated white sugar
For the Cake Batter
Preheat the oven to 350°F with the rack placed in the middle. Grease and flour a 9x13x2" baking pan; or use a piece of parchment paper to line it.
In a medium bowl, whisk the flour, baking powder, and salt.
In the bowl of a stand mixer or a large bowl for mixing with a hand mixer, cream together the butter, granulated white sugar and light brown sugar on medium-high speed until fluffly, about 2 minutes. Scrape down the sides and bottom of the bowl halfway through with a spatula.
While the mixer is running, add the eggs one at a time until each one is incorporated. Decrease the speed and add half the flour until incorporated, then add the next half. Mix and increase the speed to medium for a minute.
In a separate small bowl, whisk the milk, sour cream and vanilla extract. Add this into the mixer bowl over medium speed and mix until combined. Use a spatula to scrape the sides and bottom of the bowl and mix to finish.
Toss half of the frozen blueberries with 1 teaspoon flour and carefully fold into the batter. Use a light hand and few strokes to prevent the berries from bleeding too much and turning your cake green.
Pour batter into prepared pan and spread the top evenly. Scatter the remaining frozen blueberries over the cake batter.
For the Topping: Stir the cinnamon and sugar in a small bowl and sprinkle over the batter with blueberries on top.
Place the pan in the preheated oven and bake for 40-45 minutes, rotating the pan 180° halfway through. The cake is done when a toothpick or cake tester inserted in the center comes out clean. The top will be golden brown. Cool the cake in the pan for 20 minutes before serving.
This cake will keep for up to 3 days at room temperature; less during the warmer months.