In a large castiron skillet- toss peaches with 2 tbsp or sugar, lemon juice, and cinnamon. Please your skillet on a large rimmed baking sheet.
In a large mixing bowl- whisk together flour, brown sugar, remaining 1/4 cup sugar, and salt. Using a pastry cutter (or two butter knives), mix together butter and flour mixture until it resembles coarse crumbs. Add oats, stir to combine.
Spread oat/flour mixture over peaches and bake until peaches are bubbling and topping is golden brown.
Let cool for 10 minutes before serving. Serve with homemade vanilla ice cream.