Heat the oven to 400°F and grease a 12-cup muffin tin.
Prepare the crumble topping: In a medium bowl, whisk together flour, brown sugar, and cinnamon. Add coconut oil and mix until crumbly. Be careful not to overmix.
Mix the muffins: In a large bowl, whisk together all-purpose flour, whole wheat flour, almond flour, baking powder, apple pie spice, and salt.
In another bowl, vigorously whisk almond milk, applesauce, sugar, avocado oil, eggs, and vanilla.
Combine wet and dry ingredients, folding in the diced apples. Use a ⅓-cup measuring cup to scoop batter into muffin cups. Sprinkle crumble topping on each. Bake for 17 to 22 minutes, or until a toothpick comes out clean. Cool for 10 minutes, then transfer to a wire rack to cool completely.
Make the glaze: Whisk together powdered sugar and 1 tablespoon almond milk until smooth. If too thick, add more almond milk, 1 teaspoon at a time, until it reaches a drizzleable consistency. Drizzle over the cooled muffins. Enjoy!