Begin by melting the butter for the crumb topping. Cool slightly.
¼ cup butter, melted
In a small bowl combine the flour, brown sugar, and cinnamon. Add the butter and stir until everything is well moistened and crumbs form. Set aside.
¾ cup flour, ½ cup packed brown sugar, ¼ teaspoon cinnamon
Make the muffins:
Preheat the oven to 425℉. Line a muffin tin with paper liners and set aside.
Melt the butter and allow to cool to touch.
½ cup butter, melted
In a medium bowl whisk the flour, baking powder, baking soda, and salt.
2 cups flour, 1 teaspoon baking powder, ½ teaspoon baking soda, ¼ teaspoon salt
In a large bowl whisk together the melted butter, sugar, milk, and egg.
¾ cup sugar, ½ cup milk, 1 large egg, 2 teaspoons vanilla extract
Add the dry ingredients to the wet ingredients and stir with a rubber spatula until combined. Gently fold in the diced peaches and mix well, making sure the flour is incorporated but being careful not to over mix.
2 cups diced fresh peaches, peeled and pitted
Use a large cookie scoop, divide the batter between 12 muffin cups. Evenly distribute the crumb topping among the muffin cups. Gently press the topping into the batter.
Bake at 425℉ for 5 minutes then reduce the temperature to 350℉ and bake 13 to 15 minutes longer. Do not open the oven door. Check for doneness with a toothpick.
Remove the muffin pan from the oven and place on a cooling rack to cool completely. Remove from the pan and dust cooled muffins with confectioners' sugar.
Confectioners' sugar for dusting muffins
Notes
If you prefer a glaze you can make my confectioners' glaze. Use 1 cup of powdered sugar and 2 tablespoons of half and half. Whisk together and drizzle over cooled muffins.