Preheat the oven to 300°F (150°C). Place peeled garlic in a baking dish with rosemary and cover with olive oil. Bake for 45 minutes to 1 hour until golden and tender.

Transfer cooled confit garlic to a mixing bowl and blend with room temperature butter until smooth. Refrigerate until slightly firm.

Bring salted water to a boil and cook pasta according to package instructions, undercooking by one minute. Reserve 1/2 cup pasta water, then drain.

In a skillet over medium heat, melt the garlic butter. Add black pepper and reserved pasta water, stirring until emulsified.

Add drained pasta to the skillet, tossing to coat. Cook for an additional minute. Serve with grated Parmesan, extra pepper, and olive oil.