This is taken from the a recent issue of Vegetarian Times, with a few modifications of my own. I've used it in ravioli and on lasagna, and it tastes marvelous -- I'm sure it'd also be good in stuffed shells and/or manicotti.
15oz pkg extra-firm tofu, drained
1/2 cup (5 oz.) cooked spinach, drained (optional)
1/4 cup fresh basil
1 Tbsp garlic powder
2 Tbsp olive oil
1 Tbsp dried oregano
1/4 tsp salt
1/4 tsp ground black pepper
1/2 Tbsp nutritional yeast (optional)
1/2 Tbsp lemon juice, or to taste
Combine all ingredients in a food processor.
Ingredient Notes: When you buy the tofu, make sure you're getting the kind that's packed in water, as opposed to the kind that comes in those little vacuum-packed cardboard blocks. They have a totally different texture.