Prawns With Crab Sauce

• 4 heinz
• 1/2 cub crab meat
• 6,800 gr green onion
• 425 ml evaporated milk
• 200 gr crab meat
• 170 gr margarine melt
• 160 gr salt
• 55 gr cheddar cheese
• 40 gr margarine
• 32 gr flour