Chop the onion and mince the garlic, add to a large pot with the olive oil. Bring to a simmer on medium heat until fragrant (about 5 minutes). Chop the mushrooms and set aside. Let the cauliflower thaw out while pasta is cooking.
Add the pasta, vegetable broth, coconut milk, mushrooms and pinch of salt and pepper, cook on medium heat with the lid on watching carefully so it doesn't boil over for about 9-12 minutes. (It will cook without the lid, it will just take longer, sometimes I don't use the lid if I can't be on top of watching it from boiling over).
Add the spinach, cauliflower, nutritional yeast and cook another 7 minutes with the lid still on. If it looks like not enough liquid add ½-2 cups more, it should be enough liquid to cook the pasta without it being soupy, it should have some liquid though because when you add the nutritional yeast ad the end it will absorb some liquid and make it creamy. Check for desired texture, cauliflower heated and spinach is wilted. Make sure pasta is fully cooked.
Serve immediately. Store leftovers in the fridge up to 3 days. Re-heat in the stove top with a splash of vegetable broth or in the microwave.
Video
Notes
Coconut Milk: Be sure to use coconut milk from the can, it's creamier than the fridge section coconut milk. You can sub Cashew Cream instead if you would like, simply blend plain raw cashews in a high speed blender until smooth, ½ cup cashews to 1.5 cups water.Pasta: Use large pasta shapes, small varieties are more likely to stick to the bottom of the pan. I do not recommend gluten free varieties because they tend to foam up and usually need to be rinsed after cooking. If using small pasta just be sure to stir more often. Pot: Since it gets cooked with the lid on be sure to stay close by, if you have the heat on too high it could bubble over so just keep an eye on it. You can cook this without the pot lid but it will take longer time to cook, I have tested it and it's almost double the time for cooking the pasta.To Double the Recipe: If you double the recipe be sure to use a large pot, the tall ones with wide surface space, the pasta needs enough room to spread out otherwise you won't have enough liquid.Makes 4 small side dish servings or 2 main dish servings.