Preheat your oven to 350°F (175°C).
In a large bowl, toss sliced apples with sugar, cinnamon, and lemon juice.
Spread the apple mixture evenly in a greased baking dish.
In another bowl, combine flour, oats, brown sugar, salt, and nutmeg.
Add the softened butter to the dry ingredients and mix until crumbly.
Sprinkle the crumble topping evenly over the apples.
Bake in the preheated oven for 30-35 minutes until golden brown.
Check for doneness; apples should be tender.
Let cool for a few minutes before serving.
Serve warm, possibly with vanilla ice cream or whipped cream.