Hot Hamburger Sandwich - Cooking like a Boss

Traditional Canadian comfort food. It's a burger on top of a slice of bread covered in gravy. Much nicer than it deserves to be! Serve with garden peas and chips.

10 medium onions	dice	fry in burger pan until golden	fry until mushrooms golden	melt	stir in	stir in	season	return burgers to pan	cover and simmer until cooked through	top
oil
20cups 4.73l 4732ml 8.33pint 315tbsp 946tsp mushrooms	slice
10tbsp 0.15l 150ml 30tsp 0.634cup 0.264pint butter
10tbsp 0.15l 150ml 30tsp 0.634cup 0.264pint flour
1875ml 1 ⁷⁄₈l 125tbsp 375tsp 7.93cup 3.3pint beef broth
5tbsp 0.075l 75ml 15tsp 0.317cup 0.132pint marmite
burgers
2500g 2 ¹⁄₂kg 5.51lb 88.2oz minced beef	mix	form into 20 patties	brown	remove to plate
5tbsp 0.075l 75ml 15tsp 0.317cup 0.132pint worcestershire sauce
5tbsp 0.075l 75ml 15tsp 0.317cup 0.132pint garlic powder
salt
pepper
5tbsp 0.075l 75ml 15tsp 0.317cup 0.132pint onion powder
5 egg
oil
20 slices of white bread