Prepare pasta according to package directions for al dente pasta. When the noodles have finished cooking, drain the cooking water, reserving about 1/4 C of the water. Place the drained noodles back into the cooking pot and mix in the pesto, salting to taste. If the pasta begins to stick and clump together, add 1 TBSP of the reserved pasta cooking water at a time until the noodles separate. Place pesto noodles in a clean bowl and top with parmesan cheese.