Best Green Bean Casserole

Ingredients

• 750 g green beans (black-eyed peas)
• 1/4 cup unsalted butter 
• 1 onion (finely chopped)
• 8 mushrooms (coarsely grated) 
• 1/3 cup flour
• 1 cup of whipped cream
• 1/2 cup unsalted chicken broth
• 1/2 tsp salt
• 1 tsp. black pepper
• 1/2 tsp. soy sauce 
• 225 g fresh cheddar cheese (grated)
• 1 cup caramelized onions