Prep the apples – Peel, core, and slice them into thin wedges.
Mix the filling – In a large bowl, toss apples with sugar, cinnamon, nutmeg, cornstarch, lemon juice, and salt until coated.
Make the topping – In another bowl, stir together oats, almond flour, sugar, cinnamon, and salt. Add melted vegan butter and mix until crumbly.
Assemble – Spread the apple filling evenly in a baking dish (8x8 inches or similar). Sprinkle crumble topping over the apples.
Bake – Preheat oven to 350°F (175°C) and bake for 35–40 minutes, until the topping is golden and apples are bubbling.
Cool and serve – Let it rest for 15 minutes so the filling thickens. Serve warm with vegan ice cream or dairy-free yogurt.