Cheesy Bay Scallop Puff Pastry Shells

Preheat the oven to 375 degrees F (190 degrees C). Place pastry shells on a baking sheet.

Bake in the preheated oven until golden brown, about 20 minutes.

While pastry shells are baking, melt 1 tablespoon butter in a medium skillet over medium-high heat. Add scallops and sauté quickly on both sides until brown, 3 to 5 minutes; do not overcook. Remove from skillet and set aside.

Reduce heat to medium and melt the remaining 1 tablespoon butter in the skillet. Add mushrooms and shallots and cook until just tender, 3 to 5 minutes.

Whisk half-and-half and flour together in a bowl and add to the skillet, continuing to whisk until smooth and thick, about 5 minutes. Whisk wine, sherry, lemon juice, and mustard into the cream sauce. Stir in Parmesan cheese, tarragon, and black pepper. Add reserved cooked scallops to the skillet. Stir until just heated through, 1 to 3 minutes.

Remove pastry shells from oven and slice tops off. Fill with cheesy scallops and serve.