1/2 cup (1 stick) unsalted butter, room temperature, plus more for pan
2 cups all-purpose flour, plus more for pan
1 1/2 teaspoons baking powder
1/2 teaspoon salt
3/4 cup sugar
1 large egg
1 teaspoon pure vanilla extract
1/2 cup milk
5 cups wild or cultivated blueberries
Mrs. Kostyra's Streusel Topping
Heat oven to 350 degrees. Butter a springform baking pan, and dust with flour, tapping out excess. Set aside.
In a medium bowl, sift together the flour, baking powder, and salt; set aside.
Add reserved flour mixture, alternating with the milk, a little of each at a time, starting and ending with the flour mixture. Remove from mixer. Gently fold in blueberries.
As seen on MarthaStewart.com
1 cup all-purpose flour
1/4 cup packed light-brown sugar
1 teaspoon ground cinnamon
1/4 teaspoon salt
6 tablespoons unsalted butter, room temperature
In a medium bowl, combine flour, sugar, cinnamon, and salt. Using a pastry blender or fork, cut in the butter until fine crumbs form.
Using hands, squeeze together most of the mixture to form large clumps. The topping can be frozen in an airtight container for up to 6 months.