Vegan: Use coconut oil or vegan butter and serve with vegan ice cream.
Gluten free: Use certified gluten free oats and
oat flour, or a gluten free flour blend (I like Pamela's).
Note: If your coconut oil is in liquid form, pop it into the freezer for a little while and it'll harden.
Make ahead tip: Make the crumble topping and store it in the fridge until ready to assemble and bake.