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.

3 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
6cups 1.42l 1420ml 2.5pint 94.6tbsp 284tsp mushrooms	slice
3tbsp 0.045l 45ml 9tsp 0.19cup 0.079pint butter
3tbsp 0.045l 45ml 9tsp 0.19cup 0.079pint flour
562 ¹⁄₂ml ⁹⁄₁₆l 37 ¹⁄₂tbsp 112 ¹⁄₂tsp 2.38cup 0.99pint beef broth
1 ¹⁄₂tbsp 0.022l 22 ¹⁄₂ml 4 ¹⁄₂tsp 0.095cup 0.04pint marmite
burgers
750g ³⁄₄kg 1.65lb 26.5oz minced beef	mix	form into 6 patties	brown	remove to plate
1 ¹⁄₂tbsp 0.022l 22 ¹⁄₂ml 4 ¹⁄₂tsp 0.095cup 0.04pint worcestershire sauce
1 ¹⁄₂tbsp 0.022l 22 ¹⁄₂ml 4 ¹⁄₂tsp 0.095cup 0.04pint garlic powder
salt
pepper
1 ¹⁄₂tbsp 0.022l 22 ¹⁄₂ml 4 ¹⁄₂tsp 0.095cup 0.04pint onion powder
1 ¹⁄₂ egg
oil
6 slices of white bread