Preheat oven to 250°F.

Slice sweet potatoes into 1/16th-inch slices. Use a mandoline for even results.

Toss sweet potatoes with evoo, kosher salt and pumpkin pie spice (if you are using).

Cook for 1 hour and then flip chips over. Cook another hour.

Remove from oven and serve warm or allow to cool and store in ziplock bags for up to a week.