Preheat your oven to 375°F and grease a 9x13-inch baking dish with olive oil or cooking spray. Pat your chicken pieces dry with paper towels to encourage golden browning when sautéed.
Heat 2 tablespoons of olive oil in a large skillet over medium-high heat, then add chicken pieces and cook for 6-8 minutes until golden on the outside. Transfer the cooked chicken to a plate lined with paper towels.
In the same skillet, sauté diced onions and bell peppers for 4-5 minutes until softened and fragrant. Add diced potatoes and cook for an additional 3-4 minutes, stirring occasionally for even cooking.
In a large mixing bowl, whisk together 8 eggs and 1 cup milk until well combined, then stir in salt, black pepper, garlic powder, paprika, and shredded cheddar cheese. This cozy savory brunch recipe comes together when you fold in the sautéed vegetables, cooked chicken, chopped turkey strips, fresh spinach, diced zucchini, and fresh herbs.
Pour the entire mixture into your prepared baking dish, spreading evenly with a spatula. Bake uncovered for 40-45 minutes until the center is set and the top is lightly golden brown.
Remove from the oven and let rest for 5 minutes before serving to allow the casserole to set properly. This makes portioning much easier and more elegant.