- Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with butter or non-stick spray. 
- In a large bowl, combine the sliced peaches, 1/2 cup of the sugar, cinnamon, and lemon juice. Toss gently to coat the peaches evenly. Pour the peach mixture into the prepared baking dish. 
- In another bowl, whisk together the flour, remaining 1/2 cup of sugar, baking powder, and salt. Add the milk, melted butter, and vanilla extract. Stir until just combined; do not overmix. 
- Pour the batter over the peaches in the baking dish, spreading it evenly. Do not stir; the batter will rise while baking. 
- Bake in the preheated oven for 40-45 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean. 
- Remove from the oven and let cool for about 10 minutes before serving.