Preheat your oven to 400°F (200°C). Clean and slice the mushrooms. In a skillet, melt 2 tablespoons of butter over medium heat, add the mushrooms, and sauté until golden brown. Season with salt and pepper. Set aside.

Cook the Scallops

In the same skillet, add the remaining butter, garlic, and shallots. Sauté until fragrant. Add the scallops and sear for about 2-3 minutes on each side until golden brown. Remove from heat and add cognac, carefully igniting it if desired, to flambé. Allow to cook off.

Make the Cognac Cream

In the skillet, pour in the heavy cream and bring to a simmer. Stir in the Gruyère cheese until melted and the mixture is smooth. Season with salt and pepper to taste.

Assemble the Dish

In a baking dish, place the sautéed mushrooms at the bottom. Top with the seared scallops and pour the cognac cream mixture over everything.

Bake and Serve

Sprinkle the grated Parmesan cheese on top and bake in the preheated oven for about 10-12 minutes, or until the cheese is bubbly and golden. Garnish with chopped parsley before serving.