Blueberry Buckle

Ingredients

• Cooking spray
• 2 1/2 cups all-purpose flour (about 10 5/8 ounces)
• 1 tablespoon baking powder
• 1 teaspoon kosher salt
• 1/4 teaspoon ground nutmeg
• 1 cup granulated sugar
• 5 tablespoons unsalted butter, softened
• 1 large egg
• 1 large egg yolk
• 2 teaspoons vanilla extract
• 2/3 cup whole milk
• 3 cups fresh blueberries (about 1 pound), divided
• 1/2 cup all-purpose flour (about 2 1/8 ounces)
• 1/2 cup granulated sugar
• 3/4 teaspoon ground cinnamon
• 1/4 teaspoon ground nutmeg
• 1/4 teaspoon kosher salt
• 1/4 cup unsalted butter, softened

Steps

1. For the cake, preheat the oven to 375°F. Spray a 9-inch square baking pan lightly with cooking spray. Line the base and sides with parchment, leaving a 1-inch overhang on two opposite sides, and lightly spray the parchment too. Set aside.
2. Whisk flour, baking powder, salt and nutmeg in a medium bowl and set aside. In a large bowl, beat sugar and butter with an electric mixer on medium until fluffy, 2 to 3 minutes. Beat in egg, egg yolk and vanilla until smooth, about 30 seconds, stopping to scrape the bowl's sides as needed. On medium-low, add the flour mixture alternately with milk in 3 additions, starting and ending with flour mixture and beating just until combined each time. Gently fold in 2 1/2 cups blueberries and spread batter in the prepared pan. Scatter the remaining 1/2 cup blueberries on top.
3. For the streusel, stir flour, sugar, cinnamon, nutmeg and salt together in a medium bowl. Work in butter with a pastry blender or fingertips until crumbly, then sprinkle evenly over the batter.
4. Bake for 40 to 45 minutes, until a wooden pick in the centre comes out clean, rotating the pan halfway through. Cool in the pan on a wire rack for about 20 minutes. Lift out using the parchment overhang, discard the paper and serve warm, or cool completely on the wire rack.