Gruyere Spinach Au Gratin with Sherry-Glazed Mushrooms
Cook the mushrooms in olive oil and 2 tablespoons butter without stirring until golden on the bottom, 4 to 5 minutes, turn, add the sherry until it disappears, and season. Melt 2 tablespoons butter, stir in the flour, pour in the milk, stir until thickened, season with salt, pepper and nutmeg, and stir in the Gruyère off the heat. Press the cooked spinach dry, stir in the sauce, and top with the mushrooms, Parmesan, dots of the remaining tablespoon of butter and paprika. Bake at 375° for 20 to 30 minutes until golden and bubbling.
Creamed spinach earns its dated reputation from a single, avoidable flaw: water. Spinach holds an astonishing amount of it, and left unaddressed, that moisture thins the cream sauce into something pale and weeping. Correct for it — and add the savory weight of sherry-glazed mushrooms — and the dish transforms into the rich, glossy, deeply savory gratin you'd expect beside a great steak, not the sad spoonful of memory.
Squeeze the Spinach Dry
This is the non-negotiable step. Whether you start with thawed frozen spinach or freshly steamed, press it in a fine-mesh colander — with your hands or heavy paper towels — and wring out as much water as you physically can. That residual moisture is precisely what breaks a rich cheese sauce, so the drier the spinach, the more the Gruyère Mornay can cling to it in a thick, luxurious coat rather than sliding off into a puddle.
Searing and Deglazing the Mushrooms
The mushrooms bring the umami backbone, and they need real heat to deliver it. Lay them in a single layer in a hot, foaming pan and leave them undisturbed until they're deeply golden on the bottom before tossing — crowding or stirring too soon just steams them gray. Once browned, deglaze with dry sherry, scraping up the caramelized fond and letting the liquid cook away entirely, so all that concentrated flavor stays in the mushrooms and none of it waters down the dish.

Gruyere Spinach Au Gratin with Sherry-Glazed Mushrooms
Ingredients
- 1 (20-ounce) package frozen chopped spinach, thawed and drained (you can substitute with fresh spinach leaves)
- 2 tablespoons olive oil
- 2 tablespoons butter
- 12 ounces mushrooms, you choose the type, sliced or chopped, about 2 cups
- ΒΌ cup sherry
- 1 teaspoon kosher salt
- Β½ teaspoon coarse black pepper
- 3 tablespoons butter, divided
- 2 tablespoons unbleached all-purpose flour
- 1 Β½ cups milk
- ΒΌ teaspoon nutmeg
- 4 ounces Gruyère cheese, grated, about ½ cup
- 2 ounces Parmesan cheese, grated, about ΒΌ cup
- paprika
Method
- Heat the olive oil and 2 tablespoons butter in a pot over medium-high heat.
- Add the mushrooms. Donβt mess with them! Let the mushrooms cook until they are golden brown on the bottom, about 4 to 5 minutes.
- Turn them to cook on the second side, about 2 more minutes.
- Reduce the heat to medium and pour in the sherry. Cook until the liquid disappears, about 3 minutes more.
- Season with some of the salt and pepper. Turn off the heat.
- Preheat your oven to 375Β°.
- Cook the spinach in the microwave. Drain in a colander and use paper towels to press out excess moisture.
- Heat 2 tablespoons of butter in a pot over medium heat until melted.
- Stir in the flour and cook until the mixture begins to bubble.
- Pour in the milk and stir until the sauce begins to thicken, about 5 minutes. Season with salt, pepper, and nutmeg.
- Remove the pot from the heat and stir in the Gruyère cheese until melted.
- Place the spinach into a bowl. Pour in half of the sauce and stir. Pour in the remaining sauce and stir once more.
- Pour the spinach mixture into a casserole dish (or several smaller individual casserole dishes).
- Top the spinach mixture with the mushrooms and sprinkle with Parmesan cheese.
- Cut the remaining one tablespoon of butter into tiny pieces and dot the top of the casserole, then sprinkle with a bit of paprika.
- Cook until the top is golden and the casserole is bubbling, about 20 to 30 minutes.
The Heart of the Table
Certain side dishes exist to signal that an occasion matters — and a bubbling gratin of creamed spinach and glazed mushrooms is squarely one of them. It is celebratory food, the kind that turns a good roast into a proper feast and tells everyone at the table that tonight was worth the extra care. Generosity, here, tastes like Gruyère and browned butter.
The Art of the Host
A fine-mesh colander is quietly essential — it's what lets you wring the spinach truly dry. Beyond that, a large skillet sears the mushrooms, a saucepan builds the Gruyère Mornay, and a shallow ceramic au gratin dish (or individual ramekins for a dinner party) takes it into the oven and onto the table under its golden crust.
Neighborly Grace
- The Preparation: Squeeze every drop of water from the spinach and sear the mushrooms hard before deglazing with sherry — those two moves keep the Gruyère Mornay glossy, not watery. Assemble ahead and bake under the Parmesan crust just before serving.
- The Pour: A dry sherry echoes the mushrooms, and a glass of white Burgundy flatters the Gruyère. For a non-alcoholic option, a sparkling grape or a thyme-infused sparkling water keeps it elegant.
- The Vibe: This is steakhouse creamed spinach elevated — rich, glossy, and browned on top, it belongs beside a roast or a holiday centerpiece, spooned out while bubbling.