SERVES 8. This savory baked omelet combines sharp cheddar and tender spinach with a crisp Parmesan coating for an elegant yet easy dinner. For a taller soufflé-style rise, use a deep soufflé dish and increase baking time slightly.
5 tablespoons unsalted butter, plus more for greasing
1/4 cup finely grated Parmesan cheese
10 eggs, at room temperature
3 cups lightly packed spinach leaves or baby kale leaves
Kosher salt and freshly ground black pepper
1/4 cup plus 2 tablespoons white rice flour
2 cups warm milk
1 1/2 cups grated medium-sharp cheddar cheese
1 tablespoon minced chives
Preheat the oven to 400°F. Butter a 12-cup gratin dish or a 10-cup soufflé dish. Evenly sprinkle the grated Parmesan along the inner sides of the dish so the cheese forms a flavorful crust as the omelet bakes.
Separate the eggs, reserving all of the whites and six of the yolks in separate bowls.
In a sauté pan over medium-low heat, cook the spinach just until it wilts, about 2–3 minutes. Add a few tablespoons of water if the greens are dry to prevent sticking. Remove from heat, let cool slightly, then squeeze out excess liquid, chop roughly, and transfer to a large bowl. Season with a generous pinch of salt and a grind of black pepper.
In a small saucepan over low heat, melt the butter without allowing it to brown. Whisk in the rice flour and cook over medium-low for about 3 minutes, stirring frequently to form a smooth roux. Gradually whisk in the warm milk and continue stirring until the mixture begins to thicken, about 1 minute.
Pour the warm milk mixture into the bowl with the chopped spinach and stir to combine. Add the six reserved egg yolks slowly, one or two at a time, whisking or stirring constantly so the yolks temper smoothly. Stir in the grated cheddar, minced chives, and 1 teaspoon of salt, mixing until evenly distributed.
In a clean large bowl or using a stand mixer with the whisk attachment, beat the reserved egg whites with a pinch of salt until stiff peaks form. Gently fold the whipped whites into the spinach-cheese mixture in three additions, taking care to preserve as much air as possible. Continue folding until no white streaks remain.
Pour the combined batter into the prepared dish, smoothing the top slightly. Place the dish in the center of the oven, immediately reduce the temperature to 375°F, and bake until the top is golden and the sides are set, about 30 minutes. For a firmer center or if using a deeper dish, bake an additional 5 minutes. Keep the oven door closed during baking to encourage the omelet to rise fully.
Remove from the oven and serve immediately for best texture and flavor.
Recipe: Harriet Trezevant. Photography: Zoe Armbruster and Blaise Gargadennec.