Leek and Mushroom Cottage Pie

1. Prepare the Oven and Onion

Preheat the oven to 350 degrees Fahrenheit. In a large skillet or Dutch oven, melt 2 tablespoons of unsalted butter over medium-high heat. Add 1.5 cups of diced yellow onion, season with salt and pepper, and sauté for about 5 to 7 minutes until soft and fragrant.

2. Cook the Leeks

Add 4 cups of chopped leeks to the pan and continue to cook with the onions for another 5 minutes or until they have softened and are still vibrant green.

3. Sauté the Mushrooms

In a separate large skillet, heat 2 tablespoons of olive oil. Add 1 pound of sliced brown mushrooms and 0.5 pounds of sliced shiitake mushroom caps. Season with salt and pepper, and sauté for 2 to 3 minutes until golden. Work in batches if necessary.

4. Add Herbs to Mushrooms

Stir in 2 teaspoons of chopped fresh thyme, 2 minced garlic cloves, and a handful of chopped parsley into the mushrooms.

5. Combine Mushroom and Onion-Leek Mixture

Combine the onion-leek mixture with the sautéed mushrooms. Whisk in 2 tablespoons of white miso. Pour in 2 cups of whole milk and the cornstarch mixture dissolved in water. Let simmer for a couple of minutes until the sauce thickens.

6. Prepare Mashed Potatoes

Boil 3 pounds of peeled and chunked potatoes in salted water until tender, about 15 minutes. Drain well, and mash with 4 tablespoons of unsalted butter and a splash of heavy cream. Season with salt and pepper to taste.

7. Assemble the Pie

Transfer the vegetable mixture into a 9-by-13-inch baking dish. Spread the mashed potatoes over the mixture. Sprinkle 1 cup of bread crumbs on top and dot with 2 tablespoons of butter.

8. Bake the Cottage Pie

Bake in the preheated oven for about 45 minutes, or until the top is golden brown and the edges are bubbling.