Ingredients

TOPPING

1/2 cup light brown sugar

1/3 cup all-purpose flour

2 tablespoons unsalted butter

1 teaspoon cinnamon

MUFFINS

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

Preparation

MAKE THE TOPPING

  1. 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. MAKE THE MUFFINS
  2. 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 hand-held 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.
  3. 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 come out clean. Remove the muffins from the pan and let cool on the rack.