Yup! You sure can. And you have options! You can easily prepare the crumble topping and freeze it until needed. If you are going to the effort, I’d double the crumble topping for use on another dessert later. Then, you can prepare the fruit the day you need the dessert. This is my preferred method of prepping in advance. You can prepare the whole blueberry apple crumble and freeze it overnight. Then, thaw overnight in the fridge before you bake. The downside to this method is that you will need to defrost the whole dessert simultaneously, meaning that your crumbles won’t be as crumbly. You can prepare, bake, and freeze the apple blueberry crumble recipe. Thaw overnight in the fridge, then pop it in a 350º oven for 30 minutes.