Juicy summer peaches make these tender muffins really shine.
Preheat oven to 350 degrees. Line a standard 12-cup muffin tin with baking cups. In a medium bowl, whisk together flour, baking powder, and salt. In a separate bowl, whisk together sugar, eggs, milk, and butter. Stir wet ingredients into dry ingredients, until just combined. Fold in peaches.
Divide batter evenly between muffin cups, adding a scant 1/4 cup to each. Top each with a slice of peach and sprinkle with sanding sugar, if desired. Bake until tops spring back when lightly touched, about 22 minutes. Cool 5 minutes in pan, then transfer to wire rack to cool completely.