Crustless Spinach & Asparagus Quiche with Gruyère

serves 6

• 1 tablespoon extra-virgin olive oil
• ½ cup chopped yellow onion
• 1 pound fresh asparagus, trimmed and cut into 1-inch pieces
• 2 cups packed baby spinach
• 2 teaspoons fresh thyme leaves
• 2 cloves garlic, minced
• 6 large eggs
• ½ cup half-and-half
• 1 tablespoon Dijon mustard
• ¼ teaspoon salt
• ¼ teaspoon ground pepper
• 1½ cups shredded Gruyère cheese

1. Preheat oven to 375°F. Coat a 9-inch deep-dish pie pan with cooking spray.
2. Heat 1 tablespoon oil in a large nonstick skillet over medium heat. 
3. Add ½ cup onion and cook, stirring often, until translucent, 2 to 3 minutes. 
4. Increase heat to medium-high and add 1 pound asparagus; cook, stirring often, until the asparagus is tender-crisp, 3 to 4 minutes. 
5. Add 2 cups spinach, 2 teaspoons thyme and 2 cloves garlic; cook, stirring constantly, until the spinach is wilted and the garlic is fragrant, 1 to 2 minutes. 
6. Remove from heat and let cool for 10 minutes.
7. Whisk 6 eggs, ½ cup half-and-half, 1 tablespoon mustard, ¼ teaspoon salt and ¼ teaspoon pepper in a medium bowl. 
8. Gently stir in the asparagus mixture and 1½ cups cheese; spoon into the prepared pie pan. Place the quiche on a rimmed baking sheet and bake until set and golden brown around the edges, 30 to 35 minutes. 
9. Let stand for 10 minutes before slicing.