Preheat your oven to 425°F (220°C).
Peel and dice the sweet potatoes into uniform cubes.
In a small saucepan, melt the butter over low heat and add the minced garlic.
Combine the sweet potatoes with the garlic butter, salt, pepper, and thyme in a large bowl.
Spread the sweet potatoes in a single layer on a baking sheet.
Roast in the oven for 25-30 minutes, flipping halfway through.
Remove from oven and check for doneness.
Serve warm, garnished with additional thyme if desired.