Preheat your oven to 350°F (175°C) and lightly grease a 9x9 inch baking dish or a 10-inch cast-iron skillet.
Peel, core, and slice the apples into ¼-inch thick slices. Toss the sliced apples with lemon juice in a large bowl to prevent browning.
In a small bowl, mix the coconut sugar, flour, cinnamon, nutmeg, ginger, and salt. Sprinkle this mixture over the apples and toss until each slice is thoroughly coated.
Combine the rolled oats, almond flour, coconut sugar, chopped nuts (if using), cinnamon, and salt in a medium bowl.
In a separate small bowl, whisk together the melted coconut oil, maple syrup, and vanilla extract until emulsified. Pour the wet ingredients over the dry ingredients and stir until crumbly clusters form.
Transfer the seasoned apples to your prepared baking dish, ensuring an even layer. Sprinkle the oat topping evenly over the apples, gently pressing it down slightly.
Bake in the preheated oven for 40-45 minutes, or until the topping is golden brown and the apple filling is bubbling at the edges. For extra browning, broil on low for the final 2 minutes - but watch carefully to avoid burning!
Allow your vegan apple crisp to cool for at least 15 minutes before serving.