Fettuccine Alfredo with Cannellini Beans

In a large skillet over medium-low heat, warm the olive oil. Add the onion and sauté until just soft, 2 to 4 minutes. Stir in the garlic, pepper flakes, and beans and continue to cook until the vegetables have softened, adding a splash of water if necessary, about 5 minutes more.
Transfer the sautéed bean mixture to a food processor. Add 1 tablespoon lemon juice and the nutritional yeast, and pulse until it reaches a chunky consistency.
Set the food processor on slow speed and gently pour in the stock, a little at a time, and continue to blend until the sauce becomes creamy. You may not need all of the stock. Season with a generous pinch of sea salt and freshly cracked black pepper. Taste and add more lemon juice, salt, and pepper, if desired.
Bring a large pot of lightly salted water to a boil, and as soon as the water boils, fold in the pasta and cook until al dente, according to package instructions.
Reserve 1/2 cup (118 ml) of the pasta cooking water from the pot and drain the pasta in a colander. Return the pasta to the pot, stir in the vegan alfredo sauce and toss gently to combine all the ingredients, adding a little of the reserved pasta water, if needed, to reach a velvety sauce consistency.
Top the fettuccine with lemon zest, chopped parsley, and freshly cracked black pepper, and serve.