Prep broccoli: Separate the stem from the head. Peel the stem then cut into bite size pieces. Cut the broccoli head into florets.
Cook: Heat butter in a pot over medium heat. Add onion and broccoli stems. Cook until onions start to turn translucent (about 5 minutes). Stir occasionally so the veggies don't burn.
Add carrots: Add celery and carrots and cook 2-3 minutes.
Add flour: Sprinkle flour over the veggies and stir for 1-2 minutes to lightly cook the flour.
Simmer: Stir in bay leaf, bouillon, water, and 250ml of soy milk. Cover and simmer for 15 minutes, stirring frequently as the liquid will thicken and start to stick to the bottom of the pot. If your liquid is evaporating too quickly, reduce the heat and add a little water as needed. The liquid should be thick but there should be enough to cook the veggies.
Add remaining ingredients (except nutritional yeast): Stir in remaining soy milk, broccoli, mushrooms, and chickpeas. Mix well, then cover and gently simmer for another 10-15 minutes until all the veggies are cooked. Stir occasionally.
Add nutritional yeast: Once all the veggies are cooked, stir in nutritional yeast. Taste and add salt/pepper as desired. If you like your stew thinner, add more soy milk. Remove from heat and serve warm with rice or bread.
Notes
Soy Milk: For best flavor, use soy milk that's made with just soybeans and water. You can usually find fresh soy milk at Japanese, Korean, or Chinese markets (I buy mine from HMart).