Mum's Impossible Pie

• 4 eggs
• 1 onion (finely chopped)
• 1 tn carnation milk
• 1 egg
• 475 ml fluid milk
• 130 gr tin of tuna
• 120 gr sugar
• 120 gr mixed vegetables (frozen)
• 110 gr margarine melted
• 45 gr flour (plain)