Mushroom Leek Gratin

This vegetable gratin combines leeks, celery root, and herbs, and is topped with Gruyère cheese and panko crumbs for a rich, earthy side dish.

• Preparation Time: 25 mins
• Cooking Time: 35 mins
• Total Time: 60 mins
• Calories: 431 Calories

Ingredients

• 4 tablespoons butter
• 2 tablespoons water, or as needed
• 1 cup panko bread crumbs
• 1 cup grated Gruyere cheese
• 1 tablespoon chopped fresh chives, divided
• 1 celery root, chopped
• 2 leeks, diced
• 3 large portobello mushroom caps, diced
• 1 tablespoon chopped fresh tarragon, divided
• 0.75 cup heavy cream
• 1.5 tablespoons all-purpose flour

Recipe Instructions

Step 1

Preheat the oven to 400 degrees F (200 degrees C).

Step 2

Melt butter in a large frying pan over medium heat. Add leeks and celery root and cook for 10 minutes. Add mushroom pieces, 1/2 of the tarragon, and 1/2 of the chives; continue cooking until mushrooms release their liquid, about 6 minutes more.

Step 3

Meanwhile, combine bread crumbs and Gruyère cheese in a mixing bowl.

Step 4

Sprinkle flour over the mushroom mixture and stir until absorbed, about 1 minute. Pour in heavy cream slowly while stirring until sauce thickens and turns evenly creamy, about 3 minutes. Add half of the bread crumb–cheese mixture to the pan and stir until the cheese begins to melt, about 2 minutes.

Step 5

Remove from heat and transfer mixture to a greased baking dish. Top with remaining tarragon, chives, and the rest of the bread crumb mixture. Drizzle with a small amount of water to moisten.

Step 6

Bake in the preheated oven until the cheese is bubbly, about 10 minutes. Serve immediately.