Combine pine nuts, garlic, basil, olive oil, and parmesan cheese in the bowl of a food processor or blender. Blend to a smooth paste and season with salt and pepper to taste.

Cook tortellini according to package directions, reserving half cup of pasta water. Drain and set aside.

Meanwhile, in a large skillet, heat olive oil over medium high heat and cook garlic until fragrant, about 30 seconds. Add the shrimp to the pan and cook until it is no longer pink, about 2 minutes per side. Stir in pesto sauce and toss with the cooked tortellini until the pasta is heated through. Add more pasta water if necessary to thin out the sauce.

Serve hot with more Parmesan cheese, if desired.