Cook pasta according to instructions and set aside.
Heat oil in a pan over medium heat. Add onions and garlic and sauté until translucent. 3-4 minutes.
Add pumpkin seeds and 1/4 cup water and bring to a boil. about 4 minutes. Cook for a further 2 minutes, then allow to cool slightly.
Meanwhile, add all the nutritional yeast ingredients to the non-dairy milk using a blender (nutritional yeast , herbs, salt, lemon, vinegar, flour, pepper, olive oil, vegetable milk). Add the onion and pumpkin seed mixture to the blender. Blend until smooth.
Return to the pan over medium-high heat. Add another 1/4 cup of water. (I use the water to rinse out the blender and add to the pan). Bring to a boil. Stir frequently to avoid lumps. The mixture thickens considerably. Cook for another minute so that the flour is well cooked. 3 to 4 minutes total. Taste carefully and adjust salt and flavor. Add more herbs as needed.
Add cooked pasta, spinach, peas and other veggies if using. Mix well. If the sauce is too thick, add a few tablespoons of water or the pasta cooking water and stir. Cover and turn off the heat. Let the noodles rest for 2-3 minutes before serving.
Top with chilli flakes and your choice of nutritional yeast or vegan parmesan.