In a large bowl, whisk together the flour, sugar, baking powder, and salt. Gradually, add in the milk and vanilla until the mixture is combined.
In a Dutch oven, combine the peaches, brown sugar, lemon juice, and lemon zest and cook until the peaches are softened.
Pour the melted butter into the baking dish, then add the peach mixture but do not stir. Top with the flour mixture then bake.