Bring a large pot of water to a boil and cook the pasta according to package directions.
Add the tomato sauce, vegetable broth, and lentils to a large skillet or saucepan. Cover and bring to a simmer stirring gently every now and then. Simmer covered for about 10 minutes until the lentils are tender.
Finish the sauce by stirring in the walnuts and all of the seasonings. You can either toss the hot pasta with the sauce, or spoon the sauce over top of the pasta. Garnish with Parmegan if desired.