Using a mandoline, knife or vegetable peeler, cut sweet potatoes into uniform slices approximately ⅛” thick. Place on paper or clean kitchen towel to absorb excess moisture and set aside.
Line 2 large, rimmed baking sheets with parchment paper. Spray paper with non-stick olive oil cooking spray before arranging sweet potato slices in a single layer on top. Sprinkle with sea salt.
Place baking sheets in oven for one hour. Remove sheets and flip each chip. Sprinkle with additional salt, if desired. Return pans to oven, being sure to rotate each sheet and place on a different rack from before.
Check on chips after 20 minutes. If they are not yet crispy, continue baking until they become crisp and golden brown. (Total baking time will vary by oven and how much moisture is in your sweet potatoes. They should be ready within another 20 – 30 minutes).
Remove from oven and cool for 10-15 minutes before serving. Once cool, store excess in an airtight container.