Preheat oven to 400 degrees F.
To a large bowl, add sweet potatoes. Into a small bowl, add olive oil, garlic, and thyme. Mix together and then pour over sweet potatoes; toss to coat.
Onto a parchment lined baking sheet, arrange sweet potatoes in an even layer. Roast 20-30 minutes, or until fork tender, stirring halfway through.
When the potatoes are out of the oven, sprinkle with parmesan and parsley.