Flippantly smash 4 garlic cloves with the aspect of a knife, simply sufficient to interrupt the pores and skin. Place the garlic, 4 recent rosemary sprigs, and the remaining 4 cups vegetable oil in a big saucepan or Dutch oven and warmth over excessive warmth till the oil is 350°F, 15 to twenty minutes. To check if oil is prepared and not using a thermometer, drop a chunk of potato into the oil. If vigorous bubbles type across the piece, the oil is prepared. In the meantime, line a rimmed baking sheet with paper towels.