Preheat your oven to 250°F (120°C). In a small baking dish, combine peeled garlic cloves and fresh rosemary, then cover them with olive oil. Bake for 45 minutes to 1 hour until the garlic turns golden and soft.

Once the confit garlic has cooled slightly, transfer it to a mixing bowl along with butter. Use a fork or a handheld mixer to blend until smooth, then refrigerate for about 30 minutes to firm up.

In a large pot, bring salted water to boil. Cook your choice of dried pasta or fresh pasta until al dente, reserving a cup of starchy pasta water before draining.

In a large skillet, melt the garlic butter over medium heat. Stir in freshly cracked black pepper and gradually add in the reserved pasta water, mixing until you achieve a silky sauce.

Add the cooked pasta to the skillet with the garlic butter sauce. Toss gently to coat each strand, then serve immediately with freshly grated Parmesan if desired.