Preheat oven to 400 degrees.
Peel the sweet potatoes and cut them into 1" thick slices.
Add the sweet potatoes, olive oil, butter, salt, pepper and garlic to the bowl, mixing well.
Place the potatoes on a sheet pan.
Cook for 30 minutes then flip potatoes and cook for 20 minutes.
Remove from the oven and toss with fresh parsley and a drizzle of extra olive oil if desired.
