Set oven to 300F.
Slice a sweet potato into thin 1/8-inch thick pieces using a mandolin or a sharp knife. Keep in mind that chips that are too thick will take longer to bake and may not become crispy.
Line a baking sheet with parchment paper and place the slices on the baking sheet.
Spray the pieces with coconut oil and sprinkle with sea salt and bake for 20 minutes at 300 F.
Remove them from the oven and flip the slices over. Bake for another 20 minutes at 300F.
Remove the chips and check for flimsy or loose slices. Set the firm slices on a rack to cool and harden, and place the flimsy slices back on the baking sheet and bake for another 10 minutes, being careful not to let the chips burn.
Continue baking in increments of 8 to 10 minutes until the chips have hardened. Allow them to cool on a rack.
Place the chips in a bowl, spray with coconut oil and sprinkle with fresh ground rosemary and garlic.