As the garlic roasts and the sugars in the cloves caramelize in the oven, the garlic develops a milder, more subtle flavor. For a tutorial for roasting garlic, check out this video here.
Peel the loose paper away from the heads of the garlic and discard. Trim about ¼” off the top of the garlic to expose the cloves.
Drizzle the garlic with 2 tablespoons (26g) of the olive oil then wrap the heads of garlic in aluminum foil. Roast until the garlic is soft when pierced with a knife, about 35 to 40 minutes.
Let cool slightly then squeeze the garlic cloves from the peels, discarding the skin.
Heat a large sauté pan over medium heat, add the remaining olive oil and heat through. Add the garlic and red pepper and mash the roasted garlic into the oil with a fork.
Bring a large pot of water to a boil. Add the pasta and cook, stirring occasionally, until al dente, about 8 to 10 minutes. Reserve 1 cup of the cooking liquid then drain the noodles and return them to the pot over medium-low heat.
Toss the noodles with the garlic-oil mixture and ½ cup of the pasta water. Sprinkle with the cheese, tossing to combine. Add half the parsley and toss once more. Serve topped with the remaining parsley.
Notes
Reserve extra pasta water and add it gradually as you toss the pasta—the starchy water helps emulsify the olive oil, roasted garlic, and cheese into a silky sauce that coats every strand.