Bring a large pot of salted water to a boil. Add Fettuccine and cook al dente or until ready, about 7-10 minutes.
Meanwhile, remove roasted bell peppers from a jar and drain them (save a liquid from a jar). Add peppers to a high speed blender along with 1/8 cup of liquid from a jar and blend until pureed. (You may want to add more liquid if the sauce is too thick).
Heat olive oil in a large non-stick skillet and over medium heat. Add onion, 1/2 teaspoon of salt and sauté until translucent, about 5-7 minutes. Stir in garlic and cook for 30 more seconds.
Stir in pureed peppers, Cayenne pepper, Italian seasoning, Maple syrup, smoked paprika and plant milk and simmer on low for 5 minutes. Taste the sauce to check if it needs more seasoning.
Meanwhile, in a small bowl combine walnuts, olives and zest.
Drain cooked pasta reserving 1 cup of cooking water and toss pasta into the sauce. If the sauce is too thick, add cooking water, 2 tablespoons at a time.
Distribute pasta among serving bowls, sprinkle with Gremolata and enjoy!