Preheat oven to 425 degrees F. Line a large baking sheet with parchment paper or foil. Grease with nonstick cooking spray.
Place the yams on the prepared baking sheet. Drizzle with olive oil and toss until well coated. Make sure the yams are in a single layer, not touching.Sprinkle with salt.
Place the pan in the oven and roast for 20 minutes.
Meanwhile, stir together the pure maple syrup and cinnamon in a small bowl.
Remove the pan from the and drizzle the maple cinnamon mixture over the yams. Stir until yams are well coated. Make sure the yams are in an even layer on the pan
Return to oven and bake for 10 to 20 minutes, depending on how crispy you like your yams. Stir halfway through to make sure they are cooked evenly. I recommend checking at 10 minutes to be safe.
Remove the pan from the oven and place sweet potatoes in a serving bowl or on a platter. Garnish with candied pecans or walnuts, if using. Serve immediately.
