Ingredients

• 6 11- to 12-ounce russet potatoes
• 1/2 cup whole milk
• 2 teaspoons minced fresh rosemary
• 6 tablespoons (3/4 stick) butter, room temperature, divided
• 8 ounces Roquefort cheese, crumbled
• Coarse kosher salt
• 4 ounces Gruyère cheese, grated

Instructions

1. Preheat oven to 350°F. Bake potatoes 30 minutes. Using fork, pierce potatoes in several places. Bake until tender, about 1 hour longer. Maintain oven temperature.
2. Meanwhile, microwave milk and rosemary in microwave-safe cup on high heat 45 seconds; let steep 30 minutes.
3. Slicing lengthwise, cut top quarter off each potato. Scoop potato into large bowl, leaving about 1/4 inch of potato in skin. Scrapepotato out of tops; discard tops. Coarsely mash potato. Add 4 tablespoons butter; mash. Mash in milk mixture, then Roquefort cheese (mixture will be slightly stiff). Season with coarse salt and pepper.
4. Divide mashed potatoes among potato skins; transfer to rimmed baking sheet. Sprinkle Gruyère cheese over potatoes, pressing slightly to adhere. Dot with butter. DO AHEAD: Can be made 4 hours ahead. Let stand at room temperature.
5. Bake potatoes until hot and tops begin to brown, about 30 minutes.