• If using individual shells or gratin dishes, arrange them on a baking sheet for easy removal. If making this into a casserole, have a 2 quart dish ready.
• Place rack in the middle position of the oven and preheat oven to 350°.

Prepare scallops:

• Place scallops, wine and a good pinch of salt in a 3 quart saucepan. Add enough water to just cover scallops. Heat until it starts to boil then remove from heat. The scallops should start to look opaque. Remove scallops with a slotted spoon into a bowl and cover. Covering will retain heat and continue to cook the scallops. Return pot to burner and heat reserved liquid to boiling and boil until reduced to about 1 cup - over is better than under. Transfer into a measuring cup. It can be the same one used for heavy cream. Just combine the two.

Make cream sauce:

• In the same (now empty) saucepan, melt the butter over medium heat and saute shallots until softened and translucent, about 5 minutes. Add the mushrooms along with a sprinkle of salt and saute until mushrooms are softened and release some of their liquid.
• Stir in the tarragon.
• Sprinkle in the flour and stir to cook flour for about 1 minute.
• Stir in the the lemon juice, the reserved liquid, and the heavy cream. Bring to a simmer and cook until thickened.
• Remove from heat and stir in ½ of the grated cheese. Taste sauce and adjust for salt.
• Add the scallops and stir to coat and to warm up scallops.

Assemble:

• Divide the scallops evenly into 6 baking shells. If making this in a casserole, transfer everything into a 2 quart shallow casserole dish.
• Divide the remaining cheese and sprinkle evenly over the baking shells or on top of casserole.
• Combine the panko and chopped parsley with the melted butter and sprinkle evenly over each shell or evenly on top of casserole.

Bake:

• Bake for about 8 - 10 minutes then broil until the crumbs are golden and toasted and the cheese is bubbly.