This creamy and savory dish is perfect for a cozy dinner or a special side that impresses. With tender mushrooms and a golden cheesy topping, it’s comfort food that’s easy to make and full of flavor.
Start by heating your oven to 400°F (200°C). In a frying pan, melt some butter over medium heat, then add the leeks and celery root. Let them cook gently for about 10 minutes until they start to soften. Toss in the mushrooms along with half of the tarragon and chives, and keep cooking until the mushrooms release their juices, which should take around 6 minutes.
While that’s going on, mix the bread crumbs and Gruyere cheese together in a bowl. Once the mushrooms are ready, sprinkle the flour over the pan and stir it in. Slowly pour in the cream, stirring constantly until the mixture turns smooth and creamy, about 3 minutes. Then, add half of the bread crumb and cheese mix, stirring until the cheese just begins to melt—this should take a couple of minutes. Turn off the heat.
Spoon the mushroom mixture into a baking dish, then sprinkle the remaining tarragon, chives, and bread crumb mixture on top. Add a little splash of water to keep things nice and moist. Pop it into the oven and bake until the cheese bubbles up and turns golden, about 10 minutes. Use a spatula to serve it up right away and enjoy!
- Choose large, fresh portobello mushrooms for the best texture and flavor.
- Avoid overcrowding the mushrooms on the baking sheet to ensure even cooking.
- Let the gratin rest for a few minutes before serving to help the cheese set.
This dish combines rich, earthy mushrooms with a creamy, cheesy topping that melts perfectly in the oven. It’s comforting and elegant at the same time, making it a great choice for both weeknight dinners and special occasions.
Serve alongside a crisp green salad or roasted vegetables for a balanced meal. It also pairs well with crusty bread to soak up any delicious juices.
Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat gently in the oven to keep the topping crispy and the mushrooms tender.
