Preheat your oven to 375°F (190°C). Prepare a muffin tin with paper liners or grease it lightly.

In a large mixing bowl, whisk together all-purpose flour, granulated sugar, brown sugar, baking powder, salt, and ground cinnamon.

In a separate bowl, whisk large eggs, then mix in vanilla extract and melted butter until well combined.

Pour the wet ingredients over the dry ingredients and mix gently until just combined.

Gently fold in diced fresh peaches using a spatula.

Spoon the batter into the prepared muffin tin, filling each liner about two-thirds full.

Bake in the preheated oven for 18-22 minutes, checking for doneness with a toothpick.

Let the muffins cool in the tin for 5 minutes before transferring to a wire rack.