- For batter:
- 6 tablespoons unsalted butter
- 1/3 cup whole milk
- 1 whole large egg
- 1 large egg yolk
- 3/4 teaspoon vanilla
- 1 1/2 cups all-purpose flour
- 3/4 cup sugar
- 1 1/2 teaspoons baking powder
- 3/4 teaspoon salt
- 2 cups fresh blueberries
- For topping:
- 3 tablespoons cold unsalted butter, cut into bits
- 1/2 cup all-purpose flour
- 3 1/2 tablespoons sugar
- Make batter: Put oven rack in upper third of oven and preheat to 375 degrees F. Generously butter muffin pans.
- Melt butter in a small saucepan over moderately low heat, then remove from heat. Whisk in milk, then whisk in whole egg, yolk, and vanilla until combined well.
- Whisk together flour, sugar, baking powder, and salt in a bowl, then add milk mixture and stir until just combined. Fold in blueberries gently but thoroughly.
- Divide batter among 12 muffin cups, spreading evenly.
- Make topping and bake muffins: Rub together all topping ingredients in a bowl with your fingertips until crumbly, then sprinkle evenly over batter in cups.
- Bake until golden and crisp and a wooden pick or skewer inserted diagonally into center of a muffin comes out clean, 18 to 20 minutes.
- Cool in pans on a rack 15 minutes, then run a knife around edge of each muffin top and carefully remove from cups. Serve warm or at room temperature.