Preheat your oven to 350°F (175°C).

Lightly grease an 8x8-inch baking dish with butter or non-stick spray. This helps prevent sticking and makes cleanup easier.

Pro Tip: If you're doubling the recipe, use a 9x13-inch dish and keep an eye on the baking time—it may take a few extra minutes.

Peel and slice the apples into thin, even slices (about ¼-inch thick).

Place the apple slices in a large mixing bowl.

Add lemon juice and gently toss to coat—this brightens the flavor and keeps the apples from browning.

Sprinkle in the granulated sugar, cinnamon, nutmeg, and flour.

Mix everything gently until the apples are evenly coated in the spice mixture.

Pro Tip: Make sure all slices are similar in thickness so they cook at the same rate and stay tender without turning to mush.

In a medium bowl, combine the rolled oats, flour, brown sugar, salt, and cinnamon.

Stir until everything is well mixed.

Add the cold, cubed butter to the dry ingredients.

Use a pastry cutter, fork, or your fingertips to cut the butter into the mixture until it resembles coarse crumbs. You should still see small bits of butter throughout—that’s what makes the topping crispy and golden.

Pro Tip: Don’t overwork the butter. Stop when the mixture holds together slightly when pinched.

Pour the coated apple mixture into your prepared baking dish.

Spread it out evenly, pressing down slightly to remove air pockets.

Sprinkle the crisp topping evenly over the apples, making sure to cover the entire surface.

Place the dish on the center rack and bake for 40–45 minutes or until the topping is golden brown and the apples are bubbling around the edges.

If the topping browns too quickly, cover loosely with foil for the last 10 minutes.

Pro Tip: Let it rest for at least 10–15 minutes after baking—this helps the filling set slightly and makes scooping easier.