Bring a large pot of salted water to a boil. Cook tortellini according to package instructions, but subtract 1 minute from the recommended time. Remember to reserve 1/4 cup of pasta water before draining.

While the pasta cooks, melt butter in a large skillet over medium heat. Add minced garlic and sauté for 1-2 minutes until fragrant, being careful not to brown it.

Pour in the heavy cream and bring to a gentle simmer. Reduce heat to medium-low and cook for 2-3 minutes until it starts to thicken slightly.

Stir in the pesto and mix until well combined. Add the Parmesan cheese and stir until melted and smooth.

Add the cooked tortellini to the sauce and gently toss to coat. If the sauce seems too thick, gradually add the reserved pasta water until you reach your desired consistency.

Season with salt and pepper to taste, and garnish with fresh basil leaves if desired.