Peel and cut the sweet potato into medium pieces. Then steam them in a steamer for about 12 to 15 minutes (until tender).
Next, cook the pasta according to the package directions. Or spiralize your zucchini (using a peeler or a spiralizer) and set aside in a medium bowl.
Place the lemon, cashews, grated garlic, nutritional yeast flakes and vegetal milk in a high speed blender. When the sweet potato are cooked, add them and blend until you reach a smooth and creamy texture. I usually stop once, scrap the side and blend again.
If you want to loosen the sauce, add up to 2 tablespoons of hot water (you can use the pasta water). This is totally optional. I usually like the sauce a bit thick.
Drain the pasta and transfer them back to the pot. Toss them with as much sauce as you wish.
If you are using zucchini noodles, toss them with as much mac and cheese sauce as you wish (no need to cook them, they will become tender with the warm sauce).
Finally, add some fresh baby spinach leaves, some chili flakes, fresh thyme and fresh ground pepper.
I usually keep the leftover of the sauce in the fridge to stir into my next meal, for my pizza or even for a snack with vegetables stick. It lasts for up to 3-4 days.