Step 1

Preheat the oven to 425°F (220°C). Line a 12-cup muffin pan with paper liners or grease with nonstick cooking spray.

Step 2

Make the streusel: In a small bowl, stir the melted butter, brown sugar, and cinnamon until smooth. Add the flour and gently mix until crumbly (not smooth). Cover and refrigerate.

Step 3

Make the muffins: In a medium bowl, whisk the flour, baking powder, baking soda, salt, cinnamon, and nutmeg. In a measuring glass, mix the sour cream and buttermilk until smooth. Set both aside.

Step 4

In a large bowl, beat the butter, white sugar, and brown sugar with an electric mixer on medium speed until light and fluffy, about 2 minutes. Turn the mixer speed to low, then blend in the eggs one at a time, followed by the vanilla.

Step 5

Alternate adding the flour and buttermilk, starting and ending with the flour. Add the peaches with the last flour addition and very gently stir until just combined.

Step 6

Divide the batter evenly between the prepared muffin cups, filling each to the top. Sprinkle the streusel topping over the muffins.

Step 7

Bake for 5 minutes at 425°F, then reduce the oven temperature to 350°F (175°C) and continue baking for 15-18 minutes, or until a toothpick inserted into the center comes out clean.

Step 8

Let the muffins cool in the pan for 5 minutes before removing to a wire rack to cool completely.

Step 9

Make the vanilla glaze: In a small bowl, whisk the powdered sugar, 2 tablespoons of milk, and the vanilla extract until smooth. If the glaze is too thick, add more milk, a teaspoon at a time, until it reaches a drizzling consistency.

Step 10

Once the muffins are cooled, drizzle the vanilla glaze over the tops. Allow the glaze to set for a few minutes before serving. Enjoy!