When it comes to baking with apples, the rule of thumb is to use firm varieties since they’ll hold up better while baking. I used a mixture of Granny Smith and Honeycrisp apples to balance the tart and sweet flavors but feel free to use any other firm apples you have on hand. The key is to slice them into about ¼ inch thick slices, so you get a little bit of apple in every bite.