- 1/2 cup light brown sugar
- 1/3 cup all-purpose flour
- 2 tablespoons unsalted butter, softened
- 1 teaspoon cinnamon
- 1 1/2 cups plus 1 tablespoon all-purpose flour
- 2 teaspoons baking powder
- 1/4 teaspoon baking soda
- 1/2 teaspoon salt
- 1 large egg
- 3/4 cup sugar
- 1 tablespoon unsalted butter, melted
- 1 rounded cup sour cream
- 1 teaspoon pure vanilla extract
- 3/4 teaspoon finely grated lemon zest
- 1 rounded cup frozen blueberries
- Preheat the oven to 375°. In a medium bowl, combine the brown sugar, flour, butter and cinnamon. Rub with your fingers to form coarse crumbs. Refrigerate until ready to use.
- Butter a 12-cup muffin pan. In a medium bowl, whisk the 1 1/2 cups of flour with the baking powder, baking soda and salt. In a large bowl, using a handheld mixer, beat the egg at medium speed until frothy. Add the sugar and melted butter and beat until pale yellow, 1 minute. Beat in the sour cream, vanilla and lemon zest until blended. Add the dry ingredients and beat at low speed until almost blended. In a bowl, toss the blueberries with the remaining 1 tablespoon of flour. Using a rubber spatula, fold the blueberries into the batter.
- Fill the muffin cups three-fourths full of batter and sprinkle with the topping. Bake for 25 minutes, or until a cake tester inserted in the center of a muffin comes out clean. Remove the muffins from the pan and let cool on a rack.
The muffins can be stored in an airtight container for up to 3 days.