Preheat oven to 374 degrees. Place butter in a 13x9" baking dish and place it in the oven. Remove dish when butter has melted (make sure it doesn't burn!).
Meanwhile, combine flour, brown sugar, baking powder, and salt in a large bowl. Add milk, stirring just until dry ingredients are moistened. Pour batter over butter in baking dish.
In a medium saucepan over high heat, bring sugar, peach slices, lemon juice, lemon zest, vanilla, cornstarch, cinnamon, and nutmeg to a boil, stirring constantly. Pour mixture over batter in pan (do not stir).
Bake in preheated oven for 40 to 45 minutes, or until golden brown. Let cobbler rest for 30 minutes before serving. Top with a scoop of vanilla ice cream and enjoy!
Recipe by Simple, Sweet & Savory at https://www.simplesweetsavory.com/easy-luscious-peach-cobbler/