I’ve had a few shots at making sweet potato chips and struggled to get them nice and crisp on the outside. Through a bit of research and trial and error I think I’ve found the two main things that stop the chips being crisp. The most important thing is making sure the chips have enough space in between them when baking. This allows the moisture from the sweet potato to evaporate. My other finding is that they seem to crispen up better when they are in the oven on their own. Not sure if either of these factors are fact or not but they worked for me and I got a crispy sweet potato with a creamy inside.