Preheat your oven to 350°F (175°C). Start by placing cubed butter in a 9x13 inch baking dish and melt it in the oven for that perfect crispy edge.
Mix in a medium bowl. Combine flour, granulated sugar, baking powder, and salt until well-blended. This will form the base of your cobbler.
Add milk and vanilla extract to the dry ingredients. Stir until smooth, creating a creamy batter that's ready to adorn your buttery dish.
Pour the batter evenly over the melted butter. Don’t stir; just let the magic happen as it will rise beautifully during baking.
Toss peach slices and blueberries with lemon juice. Spread them evenly over the batter, allowing the fruit to nestle in without mixing.
Sprinkle brown sugar evenly over the top. This will caramelize as it bakes, creating a sweet, crunchy topping that you’ll adore.
Bake for 40-50 minutes. Keep an eye on it until the top is golden brown and no longer jiggles; it should look utterly irresistible!
Cool for 15 minutes before diving in. Serve warm with a luscious scoop of vanilla ice cream for a nostalgic finish.