Step 1

Preheat the oven and prepare the pan: Preheat the oven to 375°F. Brush a 9-inch pie plate with olive oil and set it on a baking sheet.

Step 2

Whisk the eggs and cube the cheese: In a large bowl, aggressively whisk together the eggs and milk. Cube the Fontina cheese and set aside.

Step 3

Prepare the vegetables: Set a large skillet over medium-high heat. Add the olive oil to the skillet. Once the oil begins to shimmer, add the mushrooms, onion, and garlic. Sprinkle with thyme, salt and pepper. Cook until the mushrooms shrink and the onions are translucent, about 10 to 15 minutes depending upon the size of your mushrooms. Drizzle the balsamic vinegar over the vegetables and stir, cooking for another minute or two. Add the spinach, stir until wilted, this should take about 3 minutes. Taste and adjust the seasoning to your liking.

Step 4

Combine: Add the cooked vegetables to the pie plate, sprinkle with the cubed cheese, and pour the egg mixture over the top. It should be full up to the rim. Carefully transfer the baking sheet to the oven.

Step 5

Bake: Set the timer for 35 minutes and bake until the center is set. Let cool at room temperature for about 10 minutes before serving.