In a sauce pot, add Butter (5 tablespoon) and All-Purpose Flour (5 1/2 tablespoon) and stir continuously to make a rue for 5-7 minutes. If you find your rue to be a bit dry, you can add some more butter or oil.
Continue to stir until browned. Add in the Vegetable Stock (2 cup) and whisk to thoroughly dissolve.
Add in the Onion (1) and Baby Bella Mushroom (1 1/2 cup). Season with Salt and Pepper (to taste). Give everything a stir and bring to boil. Turn down to medium heat and cook covered for 25 minutes, stirring occasionally, then your gravy is ready.
Serve with biscuits for classic Biscuits and Gravy, over some delicious mashed potatoes, or however else you'd like!