Blueberry-Lemon Crumb Muffins

Preheat oven to 400 degrees F. Line a 12-cup muffin pan with paper liners or coat muffin cups with cooking spray.

To prepare crumb topping: Combine 1/4 cup flour, 1/4 cup brown sugar, 1 teaspoon lemon zest and 1/8 teaspoon salt in a small bowl. Add 2 tablespoons oil and stir until crumbly. Set aside.

To prepare muffins: Whisk whole-wheat flour, all-purpose flour, baking powder, baking soda and salt in a medium bowl. Whisk eggs and brown sugar another medium bowl until blended. Add buttermilk, oil, lemon zest and vanilla (or lemon) extract; whisk until well combined. Make a well in the center of the dry ingredients and pour in the wet ingredients; stir until just combined. Add blueberries and stir until just combined. Divide the batter among the muffin cups. Sprinkle with the crumb topping, gently pressing to adhere.

Bake the muffins until golden brown and a wooden skewer inserted in the center comes out clean, about 20 minutes. Let cool in the pan for 10 minutes, then remove to a wire rack and let cool for at least 5 minutes before serving.