01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish with cooking spray or butter.
02 - Heat olive oil in a skillet over medium heat. Sauté diced potatoes for 5–7 minutes until starting to soften. Add onion and bell pepper; cook for another 3 minutes. Stir in spinach and cook until wilted. Remove from heat and set aside.
03 - In the same skillet, cook diced bacon until crisp. Remove and drain on paper towels.
04 - In a large bowl, whisk eggs, milk, salt, pepper, and smoked paprika until well combined and smooth.
05 - Layer sautéed vegetables, cooked bacon, bread cubes (if using), and half the shredded cheese in the prepared baking dish.
06 - Pour egg mixture evenly over the layered ingredients. Sprinkle remaining cheese on top.
07 - Bake for 35–40 minutes, or until eggs are completely set and the top is golden brown.
08 - Let the casserole cool for 5 minutes before serving. Garnish with fresh chives or parsley and serve warm.