Make the Filling:

Cut the butter into a few pats and place them in a 9-inch baking dish, then pop the dish into the oven to warm until the butter melts, about 5 minutes. Set aside.

Peel the peaches, then halve them, remove the pit, slice into roughly ½-inch-thick pieces, and transfer to a large skillet.

Sprinkle brown and granulated sugar over the peaches and mix, then place on medium heat while stirring occasionally. Cook the peaches for just a few minutes until the sugars dissolve. Remove from heat and set aside.

Make the Batter and Assemble:

Mix the flour, baking powder, salt, sugar, and cinnamon in a large bowl, then pour in the milk and mix until just combined.

Transfer the batter into your baking dish and spread it out toward the edges, but do not mix with the butter.

Transfer the peaches with any liquid into your dish and spread them out evenly. Leave some gaps for the cobbler topping to rise through.

Bake for about 40 to 45 minutes. It's done when the cobbler is golden brown and springs back when pressed lightly.