Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish.
In a large bowl, mix the sliced apples, granulated sugar, cinnamon, nutmeg, and lemon juice. Transfer to the prepared baking dish.
In another bowl, combine oats, flour, brown sugar, melted butter, and salt. Stir until crumbly.
Sprinkle the oat mixture evenly over the apples.
Bake for 40-45 minutes or until the topping is golden brown and the apples are tender.
Let cool slightly before serving. Enjoy warm with vanilla ice cream or whipped cream!