Layered Mashed Potato & Mushroom Casserole

4 Ratings
  • 5 2
  • 4 2
  • 3 0
  • 2 0
  • 1 0

Fancy up regular mashed potatoes with a layer of mushroom duxelle—a sauté of finely chopped mushrooms and shallots. We omitted the traditional butter in the duxelle and added chard for a nutritional boost. Serve this hearty side in place of mashed potatoes at any holiday feast or enjoy it as a vegetarian main dish.

EatingWell Test Kitchen
EatingWell Magazine, November/December 2009; updated December 2022

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Recipe Summary

active:
1 hr 20 mins
total:
2 hrs
Servings:
12

Nutrition Profile:

Nutrition Info
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Ingredients

Directions

  • Bring 1 inch of water to a simmer in a large pot. Place potatoes in a steamer basket, cover and steam over medium-low heat, replenishing the water as necessary, until the potatoes are fall-apart tender, 20 to 30 minutes.

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  • Meanwhile, working in two batches, place mushrooms in a food processor and pulse, stopping to scrape down the sides as needed, until the mushrooms are coarsely chopped.

  • Transfer the potatoes to a large bowl. Add butter and mash until chunky-smooth. Gradually stir in buttermilk, egg and egg white and 1 teaspoon salt. Set aside.

  • Heat oil in a large skillet over medium heat. Add shallots and garlic and cook, stirring, until fragrant and beginning to soften, about 1 minute. Add the mushrooms and cook, stirring often, until they release their liquid and the pan is almost dry, 10 to 12 minutes. Add chard (or spinach) and continue to cook, stirring, until wilted, about 4 minutes. Whisk broth and flour in a small bowl. Add to the pan along with the remaining 1/4 teaspoon salt, pepper and rosemary. Cook, stirring, until the mixture bubbles and thickens, about 1 minute.

  • Preheat oven to 400 degrees F.

  • To assemble, spread half of the mashed potatoes in an even layer in a 9-by-13-inch (or similar 3-quart) baking dish. Sprinkle half the Parmesan over the potatoes. Spread the mushroom mixture on top and spread the remaining potatoes over the mushroom layer. Top with the remaining Parmesan.

  • Bake until hot throughout and the top is golden brown, about 35 minutes.

To make ahead

Assemble through Step 6, cover and refrigerate for up to 1 day. Bake, uncovered, in a 400°F oven until hot, 50 minutes to 1 hour. To reheat, bake, covered, at 350° until hot, 40 to 50 minutes.

Tip

If you're storing food in your fridge for a few hours or more, it's best to keep it in an airtight container or in a container covered tightly with foil. Foil is best at creating a barrier that doesn't let unwanted flavors in (or out) while you store your food.

Nutrition Facts

Serving Size:
about 3/4 cup
Per Serving:
192 calories; protein 7.2g; carbohydrates 32g; dietary fiber 2.9g; sugars 3g; fat 4.6g; saturated fat 2g; cholesterol 23.9mg; vitamin a iu 909.9IU; vitamin c 12mg; folate 35.7mcg; calcium 92.4mg; iron 1.2mg; magnesium 44.9mg; potassium 775.7mg; sodium 450.9mg; thiamin 0.2mg.
Exchanges:

2 starch, 1 fat
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