Preheat your oven to 350°F (175°C). Grease a 9-inch baking dish or oven-safe skillet.

Make the Apple Filling:

In a large bowl, toss the sliced apples with sugar, brown sugar, cinnamon, nutmeg, flour, and lemon juice. Mix until apples are evenly coated. Transfer the mixture into your prepared baking dish.

Prepare the Crisp Topping:

In a separate bowl, combine oats, flour, brown sugar, granulated sugar, cinnamon, and salt. Add in the cold butter cubes and use a pastry cutter or your fingers to blend until the mixture resembles coarse crumbs.

Assemble:

Evenly spread the crisp topping over the apples, covering them completely.

Bake:

Bake for 40–45 minutes, or until the topping is golden brown and the apples are bubbling underneath.

Cool and Serve:

Let cool slightly before serving. Delicious warm on its own or with a scoop of vanilla ice cream.