Soak cashews: If not already soaked, place raw cashews in a heatproof bowl and cover with boiling water. Let them soak for at least 30 minutes, or until softened. For best results, soak overnight in cold water. Drain well before using.

Cook pasta: Bring a large pot of generously salted water to a rolling boil. Add the pasta and cook according to package directions until al dente. Reserve 1 cup of the pasta cooking water before draining.

Sauté garlic: While pasta cooks, heat olive oil in a large skillet or deep pan over medium heat. Add the minced garlic and sauté for 1 minute until fragrant, being careful not to brown it.

Blend sauce: Drain the soaked cashews and transfer them to a high-speed blender. Add the vegetable broth, plant-based milk, nutritional yeast, sautéed garlic (from the skillet), onion powder, black pepper, and optional lemon juice and nutmeg. Blend on high until completely smooth and creamy. This may take 1-2 minutes, scraping down the sides as needed.

Simmer sauce: Pour the blended sauce into the skillet (the same one used for garlic, no need to clean) over medium-low heat. Stir occasionally until the sauce thickens slightly and is warmed through, about 3-5 minutes. If the sauce is too thick, add a splash of reserved pasta water until desired consistency is reached. Taste and adjust salt and pepper if needed.

Combine pasta and sauce: Add the drained al dente pasta directly to the skillet with the Alfredo sauce. Toss gently to coat the pasta evenly. If the sauce is too thick, add more reserved pasta water a tablespoon at a time until the pasta is well coated and creamy.

Serve immediately: Garnish with fresh chopped parsley or a sprinkle of vegan Parmesan cheese, if desired.