Preheat your oven to 350°F (175°C). This ensures that the crisp cooks evenly.

In a large mixing bowl, combine the sliced peaches, granulated sugar, flour, vanilla extract, and lemon juice. Toss gently until the peaches are well coated. This mixture will create a sweet and flavorful filling.

Transfer the peach mixture into a greased 9-inch baking dish, spreading it evenly across the bottom.

In another mixing bowl, combine the oats, flour, brown sugar, cinnamon, and salt. Stir until well mixed. This dry mixture will provide the base for the topping.

Pour the melted butter over the oat mixture. Use a spatula to mix until the ingredients are evenly coated and crumbly. This helps create a crunchy texture when baked.

Sprinkle the crisp topping evenly over the peach filling in the baking dish.

Place the baking dish in the preheated oven and bake for 30-35 minutes, or until the topping is golden brown and the peach filling is bubbling. This allows the flavors to meld and the topping to become crispy.

Once baked, remove from the oven and let it cool for about 10 minutes before serving. This cooling time allows the filling to set slightly.

Serve warm, optionally topped with vanilla ice cream or whipped cream for an extra treat.