3 tablespoons extra-virgin olive oil 1 cup chopped onion 2 cloves garlic, minced 1 10-ounce package white or cremini mushrooms, sliced 1 teaspoon dried thyme 1 teaspoon salt, divided 1 teaspoon ground pepper, divided 1 (10 ounce) package frozen chopped spinach, thawed and squeezed dry 18 large eggs ½ cup whole milk 1 tablespoon Dijon mustard 1 cup shredded extra-sharp Cheddar cheese Local Offers Change Oops! We cannot find any ingredients on sale near you. Do we have the correct zip code?
STEP-1
Preheat oven to 300°F. Coat a large rimmed baking sheet with cooking spray.
STEP-2
Heat oil in a large skillet over medium-high heat. Add onion; cook, stirring, until light golden, 4 to 5 minutes. Add garlic; cook, stirring, until fragrant, about 30 seconds.
STEP-3
Add mushrooms, thyme and 1/4 teaspoon each salt and pepper; continue cooking and stirring until the vegetables are tender, 5 to 7 minutes more. Stir in spinach and remove from heat.
STEP-4
Whisk eggs, milk, mustard and the remaining 3/4 teaspoon each salt and pepper in a large bowl. Stir in Cheddar. Pour onto the prepared baking sheet, then sprinkle with the vegetable mixture.
STEP-5
Bake, rotating the pan from back to front halfway, until just set, 20 to 25 minutes. Cut into 12 squares and serve.