Ingredients
Streusel Topping
1/2 cup (100g) packed light or dark brown sugar
1/2 cup (67g) chopped walnuts (or pecans)
1 teaspoon ground cinnamon
Muffins
1 and 3/4 cups (220g) all-purpose flour (spoon & leveled)
1 teaspoon baking soda
1 teaspoon baking powder
1/2 teaspoon salt
1/2 cup (115g) unsalted butter, softened to room temperature
1/2 cup (100g) granulated sugar
1/4 cup (50g) packed light or dark brown sugar
2 large eggs, at room temperature
1/2 cup (120g) sour cream or plain/vanilla yogurt, at room temperature
2 teaspoons pure vanilla extract
1/4 cup (60ml) milk
1 and 1/2 cups (250g) fresh or frozen blueberries
Instructions
Preheat oven to 425°F (218°C). Spray a 12-count muffin pan with nonstick spray or use cupcake liners. Grease/line a second pan with 2 liners because this recipe yields about 14 muffins. Set aside.
Mix all of the streusel ingredients together. Set aside.
Whisk the flour, baking soda, baking powder, and salt together in a large bowl.
Using a handheld or stand mixer fitted with a paddle or whisk attachment, beat the butter, granulated sugar, and brown sugar together on high speed until smooth and creamy, about 2 minutes. On medium speed, add the eggs one at a time, beating well after each addition. Beat in the sour cream and vanilla extract on medium speed until combined. With the mixer running on low speed, add the dry ingredients and milk into the wet ingredients and beat until no flour pockets remain. Fold in the blueberries.
Spoon the batter into liners, filling them all the way to the top. Top each with streusel, gently pressing it down into the surface so it sticks. Bake for 5 minutes at 425 then, keeping the muffins in the oven, reduce the oven temperature to 350°F (177°C). Bake for an additional 18-20 minutes or until a toothpick inserted in the center comes out clean. The total time these muffins take in the oven is about 23-25 minutes, give or take. 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.
