Preheat the oven to 180 °C (350 °F).

Wash, core, and slice the apples into 1/4‑inch thick pieces. Place them in a 9‑inch square baking dish.

In a medium bowl, combine the sliced apples with lemon juice, ground cinnamon, ground nutmeg, brown sugar, vanilla extract, and a pinch of salt. Toss gently until the apples are evenly coated.

Transfer the apple mixture to the prepared baking dish, spreading it out in an even layer.

In a separate bowl, mix rolled oats, all‑purpose flour, brown sugar, and a pinch of salt.

Add the cold butter pieces to the dry mixture. Using fingertips, crumble the butter into the oats until the mixture resembles coarse crumbs.

Evenly sprinkle the oat topping over the apple layer.

Place the baking dish in the preheated oven. Bake for 35–40 minutes, or until the topping is golden brown and the apples are tender when pierced with a fork.

Remove the crisp from the oven and let it rest for 5 minutes to allow the flavors to settle.

Serve warm, topped with a generous scoop of vanilla ice cream for a silky contrast.