Stack 20 basil leaves on top of one another, roll tightly (like a cigar), and slice thinly. Place the basil in a large mixing bowl with the tomatoes, zucchini, bell pepper, garlic, nutritional yeast, salt, black pepper, and red pepper flakes. Add the olive oil and stir well. Cover with plastic wrap and let sit at room temperature for at least one hour or up to four hours. You can also let it sit in the refrigerator for up to 12 hours. Let sit at room temperature while preparing the fettuccini.
Cook the fettuccini according to the package directions. Drain and add to the sauce. Toss to coat.