Sourdough Blueberry Muffins

Preheat the oven to 375 degrees F (190 degrees C). Line 10 muffin cups with paper liners.

For the muffins, combine blueberries and 2 teaspoons flour. Toss to coat and set aside.

Combine 1 cup flour, baking soda, cinnamon, and salt in a bowl. Set aside. Whisk sourdough starter, sugar, egg, butter, and vanilla extract together in another bowl until no streaks appear.

Add flour mixture to sourdough mixture, stirring until well combined (batter will be thick). Fold blueberries into batter.

Spoon batter evenly into the prepared muffin cups.

For the topping, combine sugar, flour, butter, and cinnamon in a bowl and mix with a fork until crumbly. Sprinkle topping over muffins.

Bake in the preheated oven until tops spring back when lightly pressed, and a toothpick inserted into the center comes out clean, 20 to 22 minutes. Cool in the pan for 10 minutes. Transfer to a wire rack to cool completely.