1. Preheat the Oven:
   Preheat your oven to 350°F (175°C) to ensure even cooking.

2. Prepare the Apple Filling:
   In a large mixing bowl, combine the sliced apples with granulated sugar, lemon juice, cinnamon, nutmeg, and flour. Toss gently until the apples are well-coated with the mixture. This will enhance the flavor and help thicken the filling as it bakes. Pour the apple mixture into a greased 9×13 inch baking dish, spreading it evenly.

3. Make the Crisp Topping:
   In another mixing bowl, combine oats, flour, brown sugar, granulated sugar, salt, and cinnamon. Stir the dry ingredients until evenly mixed. Then, pour in the melted butter and mix until the topping is crumbly and well combined.

4. Assemble:
   Evenly distribute the crisp topping over the apple filling in the baking dish. Make sure to cover the apples well for a nice, crunchy layer.

5. Bake:
   Place the baking dish in the preheated oven and bake for 35-40 minutes. You’ll know it’s done when the apples are bubbling and the topping is golden brown. If the topping is browning too quickly, you can cover it loosely with aluminum foil.

6. Cool and Serve:
   Remove the apple crisp from the oven and let it cool for about 10 minutes before serving. This short cooling time helps the filling set a bit, making it easier to serve.

7. Serving Suggestions:
   Serve warm, ideally with a scoop of vanilla ice cream or a dollop of whipped cream. The combination of warm apple crisp with cold ice cream is a delightful contrast that enhances the experience.

Tips and Variations:

• Apple Varieties: Experiment with different apple types for varied flavors and textures. A mix of tart and sweet apples usually yields the best results.
• Additions: Consider adding raisins, cranberries, or chopped nuts (like walnuts or pecans) to the apple filling for added flavor and texture.
• Spice Adjustments: Feel free to adjust the spices according to your preference. Adding a pinch of cloves or allspice can also elevate the flavor profile.
• Storage: Leftover apple crisp can be stored in an airtight container in the refrigerator for up to three days. Reheat in the oven for best results.