Heavenly Onion Casserole

• 3 sweet onoins
• 120 gr swiss cheese (shredded)
• 80 gr mushrooms (fresh)
• 28 gr butter
• 10 ml soy sauce
• 8 slices swiss cheese (sliced thin)
• 8 slices french bread (sliced)
• 1 package cream of mushroom soup
• 1 package evaporated milk