# What You'll Need:
→ Muffins
01 - 2 cups all-purpose flour
02 - 2 teaspoons baking powder
03 - 1/2 teaspoon baking soda
04 - 1/2 teaspoon salt
05 - 1/2 cup unsalted butter, melted and cooled
06 - 3/4 cup granulated sugar
07 - 2 large eggs, room temperature
08 - 1 teaspoon vanilla extract
09 - 1/2 cup whole milk
10 - 1/2 cup sour cream or plain yogurt
11 - 1 1/2 cups fresh or frozen blueberries (do not thaw if frozen)
→ Streusel Topping
12 - 1/3 cup all-purpose flour
13 - 1/3 cup packed light brown sugar
14 - 1/4 teaspoon ground cinnamon
15 - 1/4 cup unsalted butter, cold and cubed
# Steps:
01 - Set oven temperature to 400°F. Line a 12-cup muffin tin with paper liners or grease thoroughly.
02 - Combine flour, brown sugar, and cinnamon in a small bowl. Cut in cold butter with a fork or pastry cutter until coarse crumbs form. Refrigerate until needed.
03 - Whisk together flour, baking powder, baking soda, and salt in a medium bowl.
04 - In a large bowl, whisk melted butter and sugar. Add eggs one at a time, beating well after each addition. Stir in vanilla, milk, and sour cream until smooth.
05 - Gently fold dry ingredients into wet mixture until just combined, avoiding overmixing.
06 - Toss blueberries with 1 tablespoon flour to prevent sinking, then gently fold into the batter.
07 - Distribute batter evenly among muffin cups and sprinkle with streusel topping.
08 - Bake for 20 to 22 minutes until a toothpick inserted into the center comes out clean and the tops are golden.
09 - Allow muffins to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.