1 cup half-and-half (or 1/2 cup whole milk + 1/2 cup heavy cream)
1 cup shredded cheese (Gruyère, Swiss, or sharp cheddar)
1/4 cup grated Parmesan (optional)
1 small garlic clove, minced
1/2 teaspoon kosher salt
1/4 teaspoon black pepper
1/4 teaspoon dried thyme or Italian seasoning
Pinch ground nutmeg (optional)
Instructions
Heat the oven to 375°F (190°C) and place a rack in the center.
Blind-bake the crust: Prick the bottom with a fork, line with parchment, fill with pie weights, and bake for 12-15 minutes. Remove weights and parchment, and bake for an additional 5 minutes until lightly golden. Cool slightly.
Cook the vegetables: Heat oil in a large skillet over medium heat. Sauté onion for 2 minutes. Add mushrooms and cook until browned and liquid evaporates, about 5-7 minutes. Stir in garlic for 30 seconds, then add spinach and cook until wilted, about 1-2 minutes. Season with a pinch of salt and pepper. Transfer to a plate to cool and pat tomatoes dry.
Make the custard: In a bowl, whisk eggs, half-and-half, salt, pepper, thyme, and nutmeg until smooth.
Assemble the quiche: Sprinkle half the cheese over the crust, add the mushroom-spinach mix, then scatter tomatoes. Top with remaining cheese and pour in the custard, being careful not to overfill.
Bake for 30-35 minutes until edges are set and center has a slight jiggle. If crust browns too fast, shield with foil.
Rest for 10-15 minutes before slicing. Serve warm or at room temperature.
Notes
Quiche reheats well and makes for excellent meal prep. Store tightly covered in the refrigerator for 3-4 days or freeze for up to 2 months.