Back in the day when I had a freezer, I used to cut up apples for pie and put them in a pie dish. After they were frozen solid, I'd remove them to plastic bag. If I wanted to make a pie, I'd just get the crust read, pop in the frozen apples, top with spices and a bit of flour, put the top crust on, and bake. Worked well. You could do the same with apple crisp.