Slice the sweet potato into 1/8 inch slices using a food processor or mandoline.
Toss the sweet potatoes with the oil and spices and spread into a thin layer on a large rimmed sheet pan.
Bake for 20 minutes and flip. Bake for another 10 minutes, until edges are beginning to curl up and get crispy.
Remove from oven and top with beans and cheese. Return to oven until cheese is melted--about 5-8 minutes.
Meanwhile, make the Avocado Cilantro Cream. Blend the avocado, yogurt, cilantro, juice and zest of a lime, and 1 teaspoon salt in a food processor or blender until smooth.
Once nachos are out of the oven, dollop as desired with the cream.
If you are looking for crispy sweet potato chips, increase the baking time by 10 minutes per side. I like the homemade chips to still have a bit of give, leaving the sweet potato rounds to be soft on the inside and crunchy on the outside, but if you want the chips to be more sturdy, bake longer.
I love black beans and therefore chose to top the sweet potato chips with them--but you can certainly use ground beef, shredded chicken or pinto beans.
If you don't like cilantro, omit it from the avocado cream, or top these homemade nachos with sour cream and diced avocado instead.