Preheat oven to 375 with rack in the middle position.

Remove pits from peaches and slice them 1/4" thick.

Transfer to a large bowl and add 2 T dark brown sugar and 1/2 t of cinnamon if you are using. Toss to combine and let sit while preparing dough.

Cook butter in a small skillet over medium heat, stirring often until it is foamy and browned. It will also stop sputtering! Pour into an 11 x 7 baking dish.

Whisk together flour, baking powder, salt and 1 c sugar in a medium bowl. Stir in milk and vanilla, then pour over the butter into baking dish. Top with peaches and juice.

Bake cobbler until golden brown and bubbling around the edges, about 1 hour. Let cool slightly before serving but this may also be served at room temperature with a scoop of ice cream or whipped cream.