Mashed Potato and Spinach Casserole

This elegant casserole puffs into a gorgeous potato soufflé. Enjoy alongside roasted or grilled meats and your favorite vegetables.

Serves: 4Hands-on: 15 minutesTotal: 45 minutesDifficulty: Easy

Serves: 4


  • 2 Yukon Gold potatoes
  • 3 Tbsp. olive oil
  • 1 small onion, minced
  • 1 bag (16 oz.) baby spinach
  • 1⁄8 tsp. nutmeg
  • 1⁄4 tsp. onion salt
  • 1⁄8 tsp. cayenne pepper
  • 1⁄3 cup fat-free half-and-half
  • 1⁄4 cup grated Parmesan cheese
  • 4 egg whites
  • 1⁄4 tsp. cream of tartar


  • Preheat the oven to 450°F and spray a 2-quart casserole or soufflé dish lightly with nonstick spray.
  • Peel and thinly slice the potatoes, adding them to a pot of cold water as you work. Bring the potatoes to a boil over high heat, then reduce the heat and simmer until tender, about 12 to 15 minutes.
  • While the potatoes are cooking, heat 1 tablespoon of the olive oil in a large skillet over medium heat. When hot, add the onion and cook, stirring occasionally, until the onion is very tender, 10 minutes. Turn up the heat to high and add the spinach. Cook the spinach, tossing with tongs, until wilted. Remove the vegetables from the heat and allow to cool slightly, then roughly chop, squeezing out extra moisture from the spinach.
  • Drain the potatoes and return them to the hot pot; shake for 1 minute. Add the remaining 2 tablespoons olive oil, nutmeg, onion salt, and cayenne pepper; mash until smooth. Beat in the half-and-half and Parmesan cheese, then fold in the spinach mixture.
  • In a large bowl, combine the egg whites with the cream of tartar and beat until stiff peaks form. Stir a dollop of the egg whites into the potato mixture and mix. Fold in the remaining egg whites.
  • Spoon the potato mixture into the casserole. Bake for 20 minutes, then reduce the heat to 375°F and bake for another 12 to 17 minutes or until soufflé is golden brown and puffed.