Leek and Mushroom Cottage Pie

Step 1

Heat oven to 350 degrees. Put butter in a large skillet or Dutch oven over medium-high heat. Add onions and season with salt and pepper. Cook, stirring occasionally, until softened and beginning to color, 5 to 7 minutes.

Step 2

Add leeks, a little more salt and stir to combine. Cook mixture for about 5 minutes more, until leeks have lost their crunch, but are still green. Turn off heat.

Step 3

Cook the mushrooms separately (work in batches if necessary): Put olive oil in a large skillet over medium-high heat. When oil is wavy, add both kinds of mushrooms and sauté 2 to 3 minutes, until lightly browned. Season with salt and pepper. Turn off heat and stir in thyme, garlic and parsley, and toss to coat.

Step 4

Add mushrooms to onion-leek mixture, and turn heat to medium-high. Add miso and milk, and bring to a simmer. Stir cornstarch and water, add to mixture and simmer for 2 minutes, stirring, until sauce thickens. Transfer mixture to a 9-by-13-inch baking dish, and leave at room temperature.

Step 5

Meanwhile, boil potatoes in salted water until very soft, about 15 minutes. Drain potatoes and mash with 4 tablespoons butter, then stir in cream and beat until smooth. Season with salt and pepper.

Step 6

Spread mashed potatoes evenly over surface of vegetable mixture. Sprinkle with bread crumbs and dot with remaining 2 tablespoons butter. Bake for 45 minutes, until bubbling and nicely browned.