In a small non-stick skillet, whisk nutritional yeast and flour together and toast over medium heat until it smells toasty, about 4 minutes. Transfer to a medium saucepan and whisk in remaining ingredients. Bring to a boil and allow to thicken as desired. Add salt and pepper to taste. For an even thicker gravy, mix 1 tbsp of cornstarch with 2 tbsp of water and pour it in to the gravy.