Preparation

• Preheat oven to 425°F (218°C). Spray a 12-count muffin pan with nonstick spray or use muffin liners. Set aside.
• For the topping: Mix all of the topping ingredients together. Set aside.
• For the muffins: Whisk the flour, baking soda, baking powder, and salt together in a large bowl. Set aside.
• Using a handheld or stand mixer, beat the butter, granulated sugar, and brown sugar together until smooth and creamy, about 3 minutes. Add the eggs one at a time, beating well after each addition. Beat in the sour cream and vanilla extract until combined. With the mixer on low speed, add the dry ingredients and milk, beating until combined. Fold in the blueberries.
• Spoon the batter into liners, filling them all the way to the top. Spoon brown sugar topping on each and gently press it down. Bake for 5 minutes at 425°F, then reduce temperature to 350°F and bake for an additional 18-20 minutes or until a toothpick comes out clean. Cool for 5 minutes in the pan, then transfer to a wire rack.
• Muffins stay fresh covered at room temperature for a few days or in the refrigerator for up to 1 week.