Step 1: Prepare the Mushrooms

Begin by cleaning the button mushrooms. Gently wipe them with a damp cloth or a soft brush to remove any dirt. Avoid washing them under running water, as they can absorb excess moisture, which will hinder their ability to brown properly during sautéing. Once cleaned, cut the mushrooms into quarters. The size of the quarters can be adjusted based on your preference, but a uniform size will ensure even cooking.

Step 2: Chop the Aromatics

Next, prepare the shallots and garlic. Peel the shallots and finely chop them. The finer the chop, the more evenly they will cook and the smoother the sauce will be. Peel the garlic cloves and mince them finely. Mincing releases the garlic’s aromatic oils, infusing the dish with its pungent flavor.

Step 3: Sauté the Mushrooms

In a large pan or skillet over medium heat, melt half of the butter (15g or 1 tablespoon). Once the butter is melted and slightly foamy, add the quartered mushrooms. Sauté the mushrooms for approximately 5 minutes, stirring occasionally. The goal is to allow them to release their moisture and begin to brown slightly. This step enhances their earthy flavor and improves their texture in the final casserole. Once sautéed, remove the mushrooms from the pan and set them aside in a bowl.

Step 4: Sauté Shallots and Garlic

In the same pan, melt the remaining butter (15g or 1 tablespoon) along with the olive oil. The combination of butter and olive oil provides both flavor and a higher smoke point. Add the finely chopped shallots to the pan and sauté them over medium-low heat for about 2 minutes, or until they become translucent and softened. Be careful not to brown them, as this can impart a bitter taste. Once the shallots are softened, add the minced garlic and sauté for another minute, until fragrant. Watch closely to prevent the garlic from burning, as burnt garlic can also taste bitter.

Step 5: Cook the Seafood

Increase the heat to medium-high. Add the scallops and peeled shrimp to the pan with the shallots and garlic. Cook the scallops for approximately 2 minutes on each side, until they are opaque and have a nice sear. Similarly, cook the shrimp for about 2 minutes on each side, until they turn pink and are cooked through. Be careful not to overcook the seafood, as it can become tough and rubbery. The cooking time will depend on the size of the scallops and shrimp.

Step 6: Deglaze with White Wine

Pour the dry white wine into the pan. Increase the heat slightly and bring the wine to a gentle simmer. Use a spatula to scrape up any browned bits that have stuck to the bottom of the pan (this is called fond), as these bits are packed with flavor and will enhance the sauce. Allow the wine to reduce by about half, which will concentrate its flavor and add depth to the sauce. This process should take approximately 3-5 minutes.

Step 7: Add the Cream and Simmer

Reduce the heat to low and pour in the thick cream. Stir gently to combine it with the wine reduction and the other ingredients in the pan. Simmer the mixture for about 3 minutes, allowing the sauce to thicken slightly. Avoid boiling the cream, as this can cause it to separate.

Step 8: Incorporate the Mushrooms

Add the sautéed mushrooms back into the pan with the creamy sauce, scallops, and shrimp. Gently stir to combine everything and heat through for an additional 2 minutes. This allows the mushrooms to reabsorb some of the sauce and become nicely integrated into the casserole.

Step 9: Season and Finish

Season the seafood casserole generously with salt and freshly ground pepper to taste. Start with a small amount and then adjust as needed. Remember that the saltiness of the seafood can vary, so taste before adding too much. Finally, sprinkle the casserole with freshly chopped parsley. The parsley adds a fresh, herbaceous note that brightens the rich flavors of the dish.

Step 10: Serve

Serve the hot seafood casserole immediately in individual casserole dishes. This presentation adds a touch of elegance to the meal. You can also serve it from a larger serving dish if preferred.