Step 1

Pour 300ml water into a medium-sized saucepan and bring it to a simmer, then add the onion, salt and pepper to form a broth. When the water reaches boiling point, add the pale ale.

Step 2

Gently place the scallops into the broth and poach for 2-3 minutes.

Step 3

Remove the scallops from the broth, set aside and reduce the heat of the broth slightly.

Step 4

Melt 30g butter in a non-stick frying pan over a low heat, and sautée the leeks until soft.

Step 5

Add the scallops to the frying pan and toast for a minute or two each side, until golden brown. Remove from the heat and cover to keep warm.

Step 6

Meanwhile, melt 50g butter in a small saucepan and add the flour, mixing it to form a roux. Strain the broth through a sieve and pour it into pan, whisking it until silky smooth.

Step 7

Beat the egg yolk with the double cream, remove the sauce from the heat and add it to the sauce.

Step 8

Place each scallop back into its shell, top it with sliced leeks, and pour the sauce into the shell, right up to the brim.

Step 9

Put the grated cheese into a bowl and sprinkle the mustard powder over it, tossing it with your hands to ensure it coats the cheese. Sieve the mixture to remove any excess mustard powder.

Step 10

Sprinkle the grated cheese over the filled scallop shells, and sprinkle with golden breadcrumbs.

Step 11

Bake for 10 minutes in the oven on gas mark 7-8/180°C.