Preheat your oven to 350°F (175°C). In a saucepan, combine peaches, sugar, cinnamon, lemon juice, vanilla, and butter.
Cook over medium heat for 5-7 minutes until soft and syrupy. If using canned peaches, just mix and warm gently.
In a bowl, whisk together flour, sugar, baking powder, and salt. Gradually stir in the milk until smooth.
Pour melted butter into a 9x13-inch baking dish. Pour batter over the butter without stirring. Spoon the peach mixture and syrup evenly over the batter, avoiding stirring.
Bake for 40-45 minutes, until the top is golden brown and bubbly. Let cool for a few minutes. Serve warm with vanilla ice cream or whipped cream.