Preheat the oven to 375 degrees Fahrenheit.
Place the butter in a 13x9 inch baking dish and put it in the oven until melted, about 5 minutes. Remove and set aside.
In a large bowl, mix flour, 1 cup sugar, baking powder, and salt. Stir in milk just until moistened; do not overmix.
Pour the batter over the melted butter in the baking dish without stirring.
In a separate bowl, combine the remaining 1 cup sugar with peach slices and lemon juice. Toss to coat.
Pour the peach mixture over the batter in the baking dish without stirring, creating layers.
Optionally, sprinkle ground cinnamon over the top.
Bake for 40 to 45 minutes until golden brown and bubbly.
Serve warm or at room temperature, topped with ice cream or whipped cream if desired.