Preheat oven to 400 degrees F.
In small saucepan, melt unsalted butter over medium heat. Add garlic and thyme, and cook until fragrant (approximately 1-2 minutes).
Stir in cayenne pepper and maple syrup. Cook another 1-2 minutes. Set aside to slightly cool. Season with salt and pepper to taste.
In large mixing bowl, coat sweet potato slices in the cayenne maple butter using your hands or a silicone spatula.
Spray muffin tins with a light coating of non-stick cooking spray.
Layer sweet potato slices in the muffin tins until slightly above the rim.
Bake 40 minutes or until stacks are cooked and edges start to brown.
Serve warm.