Preheat oven to 375°F (190°C). Grease an 8×8 inch baking dish. Toss peaches with lemon juice, sugar, and cinnamon; spread in the dish. For the topping, mix flour, sugar, baking powder, and salt. Stir in milk and butter until just combined. Drop spoonfuls over the peaches. Bake for 40-45 minutes until topping is golden.