These Coffee Cake Muffins are the perfect blend of a moist, tender cake and a sweet, crumbly topping. They're ideal for a quick breakfast treat, snack, or even a dessert with a cup of coffee or tea. The brown sugar and cinnamon streusel topping adds a delightful crunch, making these muffins a comforting and flavorful indulgence.
Preheat the oven to 375°F (190°C) and line a 12-cup muffin tin with paper liners or grease it lightly.
Make the streusel topping. In a small bowl, mix together the flour, brown sugar, and cinnamon. Add the cold, cubed butter, and use a fork or your hands to mix until the texture resembles coarse crumbs. Set aside.
Prepare the muffin batter. In a large bowl, whisk together the flour, granulated sugar, brown sugar, salt, and baking powder.
In another bowl, whisk together the melted butter, milk, sour cream, eggs, and vanilla extract until smooth.
Combine the wet and dry ingredients. Pour the wet ingredients into the dry ingredients, and stir gently until just combined. Be careful not to overmix; a few lumps are okay.
Assemble the muffins. Fill each muffin cup about 2/3 full with the batter. Sprinkle a generous amount of the streusel topping over each muffin.
Bake. Place the muffin tin in the oven and bake for 20-25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Cool. Allow the muffins to cool in the tin for about 5 minutes, then transfer them to a wire rack to cool completely.
(Optional) Add the glaze. While the muffins cool, whisk together the powdered sugar and milk for the glaze. Drizzle over the cooled muffins for an extra touch of sweetness.
Overmixing can make the muffins dense. Stir until just combined for light and fluffy muffins. Make sure your milk, eggs, and sour cream are at room temperature to help the ingredients blend smoothly. For extra texture, you can add chopped nuts, like walnuts or pecans, to the streusel topping.