Make sure your baking powder is fresh and still active. To test, put a teaspoon of baking powder in a small bowl. Sprinkle with a little warm water. If the baking powder is still good it will bubble up. (See The Difference Between Baking Soda and Baking Powder for more info.)
- 2 cups (260 g) all purpose flour (plus 1-2 Tbsp of flour for dusting the blueberries)
- 2 teaspoons baking powder
- 1/2 teaspoon salt
- 1/4 cup (1/2 stick, 57 g) unsalted butter, softened
- 3/4 cup (150 g) sugar
- 1 large egg
- 1/2 cup (120 ml) milk
- 1 pint (550 ml) blueberries
- 1/4 cup (57 g) unsalted butter, softened
- 1/2 cup (100 g) sugar
- 1/3 cup (45 g) all purpose flour
- 1/2 teaspoon cinnamon
1 Preheat the oven to 375°F (190°C). Butter the inside of an 8-inch springform pan. Set aside.
2 Whisk together the 2 cups of flour, the baking powder and the salt in a medium bowl.
3 Using a stand mixer (or by hand with a wooden spoon) beat together the butter and sugar until fluffy, about 3 minutes. Beat in the egg.
4 Add the flour mixture in 3 parts, alternating with the milk. Toss the berries with the remaining 1 to 2 tablespoons of flour (to separate and scatter evenly throughout the batter) and fold in. Pour batter into the prepared pan. Set aside.
5 Combine ingredients (butter, sugar, flour, cinnamon) for topping with a fork (or by hand) to make crumbly mixture. Sprinkle this over the batter.
6 Bake for one hour, then test for doneness by gently inserting a fork. If it does not come out clean, give the cake another 5 to 10 minutes to bake.
7 When the cake has cooled, run a knife around the edges and lift the cake out of the pan.