1. Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking dish with butter or non-stick spray.
2. In a large mixing bowl, combine the sliced peaches, granulated sugar, lemon juice, and vanilla extract. Toss gently to coat the peaches evenly.
3. Transfer the peach mixture to the prepared baking dish, spreading it out evenly.
4. In another bowl, mix together the flour, oats, brown sugar, cinnamon, and salt. Pour in the melted butter and stir until the mixture resembles coarse crumbs.
5. Sprinkle the oat mixture evenly over the peaches, covering them completely.
6. Bake in the preheated oven for 35-40 minutes, or until the topping is golden brown and the peach juices are bubbling around the edges.
7. Allow the crisp to cool slightly before serving. This will give the juices a chance to thicken up a bit.

One tip I’ve learned over the years is to use a mix of firm and slightly overripe peaches to get both structure and sweetness in the dish. And don’t worry too much about perfect peach slices; this dessert is all about rustic charm.