1 teaspoon minced fresh thyme or 1/2 teaspoon dried thyme
1/2 teaspoon kosher salt
1/4 teaspoon coarsely ground pepper
4 large eggs, room temperature
1-1/2 cups 2% milk
1/2 cup all-purpose flour
1/4 teaspoon cayenne pepper
2 cups shredded sharp white cheddar cheese
1/4 cup grated Parmesan and Romano cheese blend
1 tablespoon butter
1 tablespoon minced fresh chives
Preheat oven to 400°.
Place butternut squash in a 12-in. cast-iron skillet. Drizzle with oil. Sprinkle with rosemary, thyme, salt and pepper; toss to coat. Roast until just tender, 15-20 minutes. Remove from pan and keep warm.
In a large bowl, whisk eggs, milk, flour and cayenne; stir in cheeses. Place butter in same skillet; place skillet in oven until butter is melted, 1-2 minutes. Carefully tilt pan to coat bottom and sides with butter. Pour egg mixture into skillet; top with roasted squash.
Bake until puffed and edges are browned, 30-35 minutes. Let stand 15 minutes before cutting. Sprinkle with chives and additional Parmesan and Romano cheese blend.