Preheat oven to 425 degrees and spray a rimmed baking sheet with cooking spray.
Peel the sweet potatoes and cut into a 1/2 to 1-inch dice.Peel the garlic cloves and crush them slightly with the side of a knife.
Place sweet potatoes and garlic on prepared baking sheet. Drizzle with olive oil. Use a spoon to stir the sweet potatoes until evenly coated. Spread out in a single layer.
Sprinkle with rosemary, salt, pepper, and cinnamon.
Bake for 30 to 35 minutes, stirring halfway through.
Notes
Note: Once cooked, you can either keep the garlic cloves whole, or chop them into smaller pieces.