Most apple varieties work for this recipe, though I'd steer clear of softer, mealier varieties like Red Delicious and McIntosh, which could cook down into mush. I tend to use one tart apple (like Granny Smith) and one sweet apple (like Honeycrisp). I use this same half tart/half sweet trick pretty much every time I bake with apples, whether I'm making apple pie or apple cinnamon bread.