Mince the onion and microwave it uncovered at 600W for 1 minute. Let it cool and drain excess moisture. Separate scallop flakes from the canned juice.

Heat butter in a pan over medium heat, add flour and mix well. Gradually add milk and scallop juice, stirring until smooth and thickened.

Add the onion, scallop flakes, salt, and pepper to the sauce. Simmer on low heat until bubbling.

Transfer the mixture to a flat tray, smooth it out, and cover with cling wrap. Chill in the refrigerator for 1 hour.

Divide the mixture into 6 portions, shape into rounds, and chill for 15 minutes. Coat each piece in flour, beaten egg, and breadcrumbs.