Scallops au gratin (Coquilles Saint-Jacques) is an elegant yet easy French dish with tender scallops in a creamy sauce, topped with gruyere and breadcrumbs.
In a medium saucepan over medium heat, bring the seafood stock and white wine to a simmer. Then lower heat to low and add the scallops. Poach the scallops in liquid for 1½ minutes. Reserve the cooking liquid.
Use a slotted spoon to remove the poached scallops. Slice the scallops and set aside.
Heat a large sauté pan over medium heat. Add the butter and allow to melt, then add the shallot and sauté until tender, about 3 minutes. Add the flour and stir to combine, letting the flour cook for about 1 minute. Add 1 cup (250g) of the poaching liquid and whisk to combine. Let cook, stirring occasionally until thickened, about 2 minutes.
Whisk in the heavy cream followed by the lemon juice. Season to taste with salt.
Add the chopped scallops to the creamy sauce and stir to combine.
Portion out the scallops and sauce among gratin dishes or scallop shells.
For the breadcrumb topping and serving:
In a small bowl stir together the breadcrumbs, butter, cheese, parsley and tarragon. Evenly divide it over the top of all the scallops.
Arrange rack in the top ¾ of the oven. Broil the scallops until the mixture is bubbling and golden brown, about 2 to 3 minutes. Serve hot.
Notes
Swaps and substitutions
While I love preparing the scallops St. Jacques in scallop shells, it can also be prepared in gratin dishes.