In a large pot, bring vegetable broth to boil over high heat. Add tomato paste and stir in to combine. Add saffron, if using, red pepper flakes and fennel.
With the broth still on the boil, add your pasta. Cook just until al dente. That means to the tooth, people. The pasta should yield when you bite it.
Drain pasta into a colander with a bowl beneath to save the sauce.
You’ll see the pasta will have drunk up quite a bit of the broth and the broth will be thickened from the pasta. Cool.
Pour pasta into a large bowl. Sprinkle in nutritional yeast and toss to combine.
Add some of the sauce back into the pasta bowl, 1/2 cup at a time, where it will continue to absorb into the pasta.
You can finish with some sea salt and pepper and enjoy like this, or add the vegetable ingredients.
Toss what you like in with the pasta and add the sauce back in half-cup increments until you have the pasta of your dreams. Your nonna will understand.