Place a rimmed baking sheet on a grill; preheat to medium-low (about 325 degrees F).Advertisement
Add butter and oil to the pan and heat until melted and sizzling. Add potatoes, garlic and rosemary and cook, turning the potatoes and garlic often and adjusting the heat as necessary, until tender and golden, 20 to 30 minutes.
Discard the rosemary. Using tongs, transfer the potatoes and garlic to a serving dish and season with salt and pepper.
3 fat, 2 starch