Preheat your oven to 375°F (190°C) and lightly grease your baking dish to prevent sticking.
Peel the peaches using a peeler, then slice them into even pieces and place them in a mixing bowl.
Toss the sliced peaches with sugar and cinnamon until evenly coated. Let sit for a few minutes to allow the juices to start flowing.
Pour the sweetened peaches into the prepared baking dish, spreading them out into an even layer.
In a separate bowl, combine oats, flour, brown sugar, salt, and a pinch of cinnamon if desired.
Cut in the cold butter using a pastry cutter or fork, working quickly until the mixture resembles coarse crumbs that are buttery and fragrant.
Sprinkle the crumbly topping evenly over the peaches, covering most of the fruit but leaving some gaps for juices to bubble through.
Bake in the oven for 35-40 minutes, until the topping is golden brown and bubbling around the edges.
Remove the crisp from the oven and let it rest for about 5-10 minutes to allow the juices to settle and make serving easier.
Serve warm, perhaps with a scoop of vanilla ice cream or a dollop of whipped cream for extra indulgence.