In a medium bowl, whisk flour, ½ cup sugar, baking powder, and salt together until combined.
Stir in milk just until combined.
Pour batter over butter, but do NOT stir.
Bring remaining ½ cup sugar, peach slices, and lemon juice to a boil over medium-high heat, stirring constantly.
Remove from heat.
Pour peach mixture over batter, but do NOT stir.
Sprinkle cinnamon over the peaches.
Bake for 30-40 minutes, or until golden brown.
Serve warm or at room temperature.
If you prefer a less sweet cobbler, you can reduce the sugar in the peach portion to ¼ cup. If you have very sweet peaches, you may decide to omit the sugar in that portion. However, do not omit the sugar in the cobbler portion.