# What You'll Need:
→ Muffin Batter
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
→ Streusel Topping
12 - 1/3 cup all-purpose flour
13 - 1/3 cup light brown sugar, packed
14 - 1/4 teaspoon ground cinnamon
15 - 1/4 cup unsalted butter, cold and cubed
# How to Make It:
01 - Preheat oven to 400°F and 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 mixture resembles coarse crumbs. 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 until blended. Add eggs one at a time, beating well after each. Stir in vanilla, milk, and sour cream until smooth.
05 - Gently fold the dry ingredient mixture into the wet ingredients until just combined, avoiding overmixing.
06 - Toss blueberries with 1 tablespoon flour to prevent sinking, then gently fold into the batter.
07 - Divide batter evenly among muffin cups and sprinkle each with a generous amount of streusel topping.
08 - Bake for 20 to 22 minutes until a toothpick inserted in the center comes out clean and tops are golden brown.
09 - Allow muffins to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.