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, about 5–7 minutes. Transfer to paper towels to drain excess grease.
04 - In a large bowl, whisk together eggs, milk, salt, pepper, and smoked paprika until fully combined and smooth.
05 - Spread sautéed vegetables, cooked bacon, and bread cubes (if using) evenly in the prepared baking dish. Top with half the shredded cheese.
06 - Pour egg mixture evenly over the filling, ensuring it distributes throughout. Sprinkle remaining cheese on top.
07 - Bake for 35–40 minutes until eggs are completely set and the top is golden brown. A knife inserted in the center should come out clean.
08 - Let the casserole cool for 5 minutes before cutting. Garnish with fresh chives or parsley and serve warm.