Bring a large pot of water to a boil and salt the water generously. Add the pasta and cook according to the package directions just until al dente - don’t cook until soft, it will continue cooking in the sauce!
Meanwhile, slice or crumble the vegan sausage, depending on your variety (Beyond Meat crumbles; Field Roast slices).
Heat a large nonstick saute pan over medium-high heat. Once hot, add a touch of olive oil (if needed) and add the vegan sausage (if you have a good nonstick pan, you likely won't need oil). Cook, stirring occasionally, until the sausage is nicely browned.
While the sausage is cooking, mix the marinara sauce with the tomato paste, oregano, red pepper flakes, and nutritional yeast and stir to combine.
Once the sausage is mostly browned, add the spinach or kale and cook for 30-60 seconds until almost wilted but still bright green. Pour in the marinara sauce mixture and toss to combine.
Use a slotted spoon to transfer the hot cooked pasta from the pot into the saute pan. Toss the pasta with the sauce and sausage and stir to combine for about 1 minute.
Sprinkle with extra red pepper flakes or black pepper before serving, and top with basil or parsley.