Preparation Steps

• Heat the oven to 375°F. Lightly coat a 9x13-inch baking dish with cooking spray or oil.
• Heat 1 tablespoon olive oil in a large skillet over medium heat until shimmering. Add 1 pound uncooked pork breakfast sausage and cook, breaking it up into small pieces with a wooden spoon, until no longer pink, 6 to 8 minutes.
• Stir in 1 diced medium yellow onion, 1 diced medium red bell pepper, and ½ teaspoon of the kosher salt. Cook, stirring occasionally, until the onion is softened, 3 to 5 minutes. Stir in 3 ounces baby spinach. Cook until wilted, about 1 minute. Transfer to the baking dish.
• Whisk 12 large eggs, 2 cups half-and-half, 1 tablespoon Dijon mustard, the remaining 1 teaspoon kosher salt, and ½ teaspoon black pepper in a large bowl until combined.
• Add 20 ounces frozen shredded potatoes and half of the shredded sharp cheddar cheese to the baking dish. Stir until combined and spread into an even layer.
• Pour the egg mixture over the potato mixture. Tilt the baking dish so the egg mixture is in an even layer if needed. Sprinkle with the remaining ¾ cup cheddar.
• Bake until a knife inserted in the middle comes out clean and the top is light golden-brown, 55 to 60 minutes. Let cool for 5 minutes before serving.