Spinach, Mushroom, & Swiss Crustless Quiche Squares Recipe

Leafy and green, spinach is a versatile superfood that is low in calories and fats and high in fiber and iron.

Just one cup gives you 56% of your daily value of Vitamin A and 14% of your daily value of Vitamin C, and there are plenty of simple and delicious ways to introduce it into your diet. It’s no wonder Popeye was such a fan! 

Spinach, Mushroom, & Swiss Crustless Quiche Squares

Recipe by Whole Foods
0.0 from 0 votes
Course: AppetizersCuisine: American



    These bite-sized appetizers make a perfect addition to any holiday party.


    • 1 16 oz.

      bag frozen chopped spinach, thawed and squeezed to remove as much liquid as possible.

    • 1 tablespoon

      extra-virgin olive oil, divided

    • 2 cups

      (about 1 onion) thinly sliced yellow onions

    • 1 pound

      button mushrooms, thinly sliced

    • 3⁄4 teaspoon


    • ½ teaspoon

      freshly ground black pepper

    • 6


    • 3⁄4 cup

      reduced-fat milk

    • 1 teaspoon

      freshly grated nutmeg

    • 1 ½ cup

      shredded Swiss cheese


    • Preheat oven to 350°F and grease a 9-inch square pan with cooking spray; set aside. 

    • Heat olive oil in a large skillet over medium-high heat. Add onion and cook until golden brown, seven to eight minutes. Add mushrooms, ½ teaspoon salt, and ¼ teaspoon pepper and cook until liquid is absorbed, 10 to 12 minutes; set aside to cool. 

    • In a large bowl, whisk together eggs, milk, nutmeg, and remaining ¼ teaspoon salt and ¼ teaspoon pepper. Add cheese, onion, mushrooms, and spinach and mix well. 

    • Transfer to prepared pan, spread out evenly, and bake until set in the middle and golden brown, about 45 minutes. Let cool 10 or 15 minutes; cut into 24 squares and serve.

    Healthy Tips

    • Go Fresh. - If you can, use fresh instead of frozen spinach, as freezing the leaves takes away some of its nutritional value
    • Turn on the heat. - Cooked spinach has more health benefits than raw. This is because if you eat spinach uncooked, your body can’t completely break down the nutrients.
    • Juice it! - Research shows that juiced spinach (like a healthy green juice or smoothie) actually provides the most amount of nutrients.

    Notes about Spinach

    How to Store Spinach

    If you have leftover uncooked spinach, the best way to store it is in a plastic bag or container lined with a dry paper towel. Avoid excess moisture, as this will cause the leaves to rot more quickly. If it’s stored correctly, you can keep it up to three weeks before it’s ready to toss.

    Spinach Season

    Spinach is a hardy green that can endure cold temperatures, making it a great option in winter. If you have a yard (or even a big pot) you can give spinach growing a shot with a cool-season garden. Late winter is one of the best times to plant spinach, so start planning now! 

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