Preheat your oven to 375°F (190°C).

In a large mixing bowl, combine the sliced apples, 1/4 cup granulated sugar, 1/4 cup light brown sugar, 1 tablespoon all-purpose flour, 1 teaspoon ground cinnamon, 1/4 teaspoon ground nutmeg, 1/4 teaspoon salt, and 1 tablespoon lemon juice. Toss gently to ensure the apples are evenly coated.

Melt the 2 tablespoons of unsalted butter in a 10-inch cast iron skillet over medium heat on the stovetop. Once melted, add the apple mixture to the skillet, spreading it into an even layer.

In a separate medium bowl, combine 1 cup all-purpose flour, 1/2 cup rolled oats, 1/2 cup light brown sugar, 1/4 cup granulated sugar, 1/2 teaspoon ground cinnamon, and 1/4 teaspoon salt. Whisk or stir these dry ingredients thoroughly to combine.

Add the cold, cubed butter to the dry ingredients. Use a pastry blender, your fingertips, or two forks to cut the butter into the mixture until it resembles coarse crumbs with some pea-sized pieces remaining. This creates the signature crisp texture.

Evenly sprinkle the prepared crisp topping over the apple filling in the skillet.

Transfer the skillet to the preheated oven and bake for 35-40 minutes, or until the apples are tender when pierced with a fork, the filling is bubbling around the edges, and the topping is golden brown and delightfully crisp. If the topping begins to brown too quickly, you can loosely tent the skillet with aluminum foil.

Carefully remove the skillet from the oven and let it cool for at least 10-15 minutes before serving. This allows the hot apple filling to set slightly.

Serve warm, optionally with a generous scoop of vanilla ice cream or a dollop of freshly whipped cream for an extra treat.