Preheat the Oven:
Preheat your oven to 350°F (175°C). Lightly grease an 8x8-inch baking dish.
Prepare the Apples:
Peel, core, and slice the apples into thin, even slices. Place them in a large bowl. Add the granulated sugar, brown sugar, flour, cinnamon, nutmeg, and lemon juice. Toss until the apples are evenly coated.
Transfer to Baking Dish:
Spread the apple mixture evenly into the prepared baking dish.
Make the Topping:
In another bowl, mix the oats, flour, brown sugar, cinnamon, and salt. Pour in the melted butter and stir until the mixture forms a crumbly texture.
Assemble and Bake:
Sprinkle the crumble topping evenly over the apples. Bake in the preheated oven for 40-45 minutes, or until the topping is golden brown and the apple filling is bubbling.
Cool and Serve:
Allow the apple crisp to cool slightly before serving. Pair it with a scoop of vanilla ice cream or a dollop of whipped cream for the ultimate dessert.