Seafood Thermidor

• 1 quartered onion
• 1 lemon
• 130 gr crabmeat
• 60 ml milk
• 60 ml wine (white)
• 55 gr soft bread crumbs
• 28 gr mozzarella cheese (shredded)
• 28 gr butter
• 24 gr flour
• 10 gr parmesan cheese