Cut the top 1/4 inch off the garlic. Place garlic on a piece of aluminum foil. Drizzle oil over the top. Wrap in the foil and roast for 40 - 45 minutes or until browned and soft. Remove from oven. Allow to cool. Use a fork to remove cloves. Mash together in a bowl.
Bring a large pot of water to boil and cook pasta according to package directions. Drain, reserve 1/2 cup pasta water.
While the pasta is cooking, melt butter in a skillet over medium heat. Add in roasted garlic and cook until garlic is fragrant, 30 seconds - 1 minute.
Stir in 1/2 of the cheese and cook just until it starts to melt. Stir in 1/2 of the cream and whisk until the cheese melts. Add in remaining cheese and cream. Continue whisking until smooth. Add pepper and parsley. If sauce appears to thick, thin with a little of the reserved pasta water.
Add hot pasta and toss to coat. Add salt if needed. Serve immediately.
Freshly grated parmesan cheese is a must! Slowly whisk in the cheese to prevent clumping. It also helps if it is at room temperature. The roasted garlic can be made in advance. This is best served the day of. The leftovers do not reheat very well because the sauce tends to separate a bit. Nutrition information for estimation purposes only.