Liz Barbour shows you how to make apple and sweet potato crisp. Follow these steps to make a delicious apple and sweet potato crisp: Chop up some apples and sweet potatoes and add place them in a baking dish. You can also top with fresh cranberries if you want to. For the topping you will need old fashioned oats, ground flax seed, brown and white sugar and butter. Mix it all together and cover the apples and sweet potato with the mixture. Bake at 375 degrees for about 45 minutes, until the topping is brown and the sweet potatoes are soft.