Caramelize the Onions: In a Dutch Oven or other heavy lidded pot, add the onions, olive oil, and sea salt. Sauté on low heat, and stir with a wooden spoon for 25 minutes until the onions begin to reduce. After 25 minutes, add the vegan Worcestershire sauce and sauté for 5 additional minutes.
Cook pasta according to package instructions.
While pasta is cooking, in a large pot heat butter over low heat. Add the garlic and sauté for 2 or 3 minutes until the garlic begins to brown. Sprinkle in the flour and stir until a thick paste forms.
Add the milk, vegetable stock, garlic salt and pepper, and parmesan cheese to the pot. Stir well until a thick sauce forms. Add the caramelized onions and pasta to the sauce, toss well, and top with parsley and black pepper if desired.
If sauce is too thick, add additional milk 1/4 cup at a time until the sauce reaches desired consistency. If sauce is too thin, add an additional tablespoon of flour until it reaches desired consistency.
Notes
To Make Your Own Unsweetened Oat Milk:
.Combine 1 cup oats, 4 cups water, and pinch of salt to a blender. Allow the ingredients to sit for 10 minutes before blending.
Blend on high for 30 seconds. Strain immediently though a fine mesh strainer, cheese cloth, or a nut milk bag. Do NOT squeeze the oat milk, let it drain naturally. Squeezing it can cause it to become slimy.
To thicken your sauce: add 1 tablespoon of water to 1 teaspoon of cornstarch in a seperate bowl, mix well to combine. Add corn starch mixture to the pasta sauce while it is warming and stir for a minute or two until it thickens.