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 on high speed 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 running on low speed, add the dry ingredients and milk into the wet ingredients and beat 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, gently pressing it down into the surface. Bake for 5 minutes at 425°F, then reduce the oven temperature to 350°F and bake for an additional 18–20 minutes until a toothpick inserted in the center comes out clean.
• Allow the muffins to cool for 5 minutes in the muffin pan, then transfer to a wire rack to continue cooling.
• Muffins stay fresh covered at room temperature for a few days or in the refrigerator for up to 1 week.