Italian Zucchini Casserole

• 600 gr zucchini
• 240 ml water
• 65 gr green pepper (chopped)
• 60 gr onion (chopped)
• 55 gr cheddar cheese (shredded)
• 55 gr margarine
• 1 package spaghetti sauce dry mix
• 1 package mushroom (pieces)
• 1 package tomato paste
• 1 slice parmesan cheese (grated)