Blueberry coffee cake with streusel
- Streusel topping
- 1/2 cup rolled oats (not instant)
- 6 tablespoons all-purpose flour
- 1/4 cup light brown sugar, packed
- 1 pinch kosher salt
- 1 pinch nutmeg, freshly grated
- 4 tablespoons (1/2 stick) unsalted butter
- 5 tablespoons unsalted butter: 1 tablespoon for greasing pan; plus 4 tablespoons (1/2 stick) melted, for the cake
- 4 cups blueberries
- 2 cups unbleached all-purpose flour
- 1 teaspoon baking powder
- 1/2 teaspoon baking soda
- 1/2 teaspoon kosher salt
- 1/2 cup whole milk
- 1/2 cup creme fraiche or sour cream
- 1/2 cup granulated sugar
- 2 large eggs, room temperature
In a small bowl, combine the oats, flour, brown sugar, salt, and nutmeg. Add the butter in pieces and, with your fingers, gently rub the dry ingredients into the butter until they are incorporated and crumbly. Refrigerate until ready to use.
Preheat the oven to 350°F. Grease a 9-inch square glass baking dish with 1 tablespoon butter. Wash and drain the blueberries; spread them out on paper towels to dry, removing any bits of leaf or stem.
In a large mixing bowl, combine the 2 cups flour, baking powder, baking soda, and 1⁄2 teaspoon salt. Stir until well mixed. In a medium bowl, whisk together the milk, crème fraîche, sugar, eggs, and 4 tablespoons melted butter. Add the wet ingredients to the flour mixture, stirring to blend well. Gently fold in the blueberries.
Spread the batter in the prepared dish. Sprinkle evenly with the streusel topping. Bake until a wooden pick inserted in the center of the cake comes out clean, 45 to 50 minutes. Cool on a wire rack at least 20 minutes before serving.