Preheat the oven to 350°F (175°C).
In a mixing bowl, combine the sliced peaches, ½ cup of sugar, and lemon juice. Toss until the peaches are well coated. Set aside to let the flavors meld.
In another bowl, whisk together the flour, remaining ½ cup of sugar, baking powder, and salt.
Add the milk, melted butter, and vanilla extract to the dry ingredients. Stir until just combined; do not overmix. The batter will be slightly lumpy.
Pour the batter into the bottom of a greased 9x13-inch baking dish.
Spoon the peach mixture over the batter, spreading it evenly. Do not stir; the batter will rise around the peaches during baking.
Bake in the preheated oven for 45 minutes or until the top is golden brown and a toothpick inserted in the center comes out clean.
Remove from the oven and let it cool slightly before serving.
Serve warm with a scoop of vanilla ice cream or whipped cream for an extra treat.