The butternut pie filling is thick so it's a bit hard to tell when it's set. I baked my pie for 30 minutes and the top cracked. When eggs are overcooked in a pie filling, it causes cracking, so next time I will check my pie at 15 minutes and keep an eye on it. At 20 minutes, eggs should be cooked and safe to eat but use your own judgement. If your pie does crack, just cool it on a rack and hide the cracks with whipped cream!