Preheat your oven to 350 degrees. Let it get fully warm before baking. Place your butter in the baking dish.
Put the dish in the oven for a bit. Let the butter melt completely. Do not let it turn brown or smoke.
Remove the dish once the butter is liquid. Set it aside on a heat-safe surface. Do not stir the melted butter yet.
Whisk the flour and sugar in a bowl. Add the baking powder and the salt. Mix them until they look like soft sand.
Pour the milk and vanilla into the bowl. Stir the mixture gently with a large spoon. The batter should be thick but pourable.
Pour this batter over the melted butter. Do not stir the batter and butter together. Let them sit in layers for the best texture.
Place your sliced peaches on top of the batter. Distribute them evenly across the whole pan. The batter will rise around the fruit later.
Sprinkle a little extra sugar and cinnamon on top. This creates a beautiful, crunchy sweet crust. It smells amazing while it bakes.
Bake the cobbler for about forty-five minutes. The top should be a deep golden brown. The fruit juices should be bubbling.