Preparation Steps

• Preheat the oven to 375°F (190°C). Lightly grease an 8-inch square baking dish or a similar shallow ovenproof dish.
• Place the sliced peaches in a large bowl. Add the granulated sugar, cornstarch, lemon juice, vanilla, 1/4 tsp cinnamon and a pinch of salt. Toss gently to coat and let sit for 10 minutes to macerate — this pulls out juices and helps the filling thicken while baking.
• While the peaches rest, make the topping: combine oats, flour, brown sugar, 1/2 tsp cinnamon and 1/4 tsp salt in a medium bowl. Cut the cold diced butter into the dry mix with a pastry cutter or rub between your fingertips until the mixture forms coarse crumbs. (Alternatively pulse 6–8 times in a food processor for a quick method.)
• Pour the peach mixture (including any released juices) into the prepared baking dish and spread into an even layer. Scatter the oat-flour crumb evenly across the top, gently pressing so it adheres in places but still remains crumbly.
• Bake for 38–42 minutes, until the filling is bubbling at the edges and the topping is deep golden brown. If you want an extra-toasty top, place under the broiler for 1–2 minutes — watch closely so it doesn’t burn.
• Remove from the oven and let the crisp rest for about 15 minutes to thicken slightly before scooping. Serve warm with vanilla ice cream or whipped cream, if desired.
• Leftovers: cover and refrigerate for up to 3 days. Reheat individual portions in the oven or microwave; a quick 5–7 minute bake at 350°F will refresh the topping.