While the oven heats, place pecans on baking sheet. Toast about 5 minutes, until slightly dark. Set aside.
Place sweet potatoes on a baking sheet with oil, salt and pepper (toss to coat). Roast 40 to 45 minutes until golden brown and tender.
Melt butter in a small saucepan, add maple syrup and cayenne. Cook for 1 minute.
Serve potatoes with a drizzle of maple butter and a sprinkle of pecans.