Preheat oven to 425 and line a roasting pan with parchment paper.
Cut the sweet potatoes into 3/4 in. thick slices and spread out on the roasting pan in an even layer.
Spray sweet potatoes with olive and place in the oven for about 25 minutes.
Take the sweet potatoes out of the oven and gently mash with a fork to slightly flatten to potatoes.
Sprinkle potatoes with garlic powder, salt, and pepper. Then place back in the oven for another 10 minutes so the outer edges crisp a little more.
Sprinkle the potatoes with parmesan and thyme. Place potatoes back in the oven to melt the cheese for 4-5 minutes.
Remove and serve with sour cream or greek yogurt.