01 - Heat butter or oil in a large nonstick skillet over medium heat.
02 - Add diced potatoes and cook, stirring frequently, until golden and tender, about 10 to 12 minutes.
03 - Add diced onion and bell pepper, if using, and sauté for 3 to 4 minutes until vegetables are softened.
04 - In a mixing bowl, whisk eggs, milk, salt, and black pepper until well combined.
05 - Reduce skillet heat to medium-low. Pour egg mixture evenly over the sautéed vegetables. Allow to set undisturbed for 30 seconds.
06 - Gently stir and fold the eggs with a spatula as they begin to set, cooking until mostly set but slightly runny, about 2 to 3 minutes.
07 - Sprinkle shredded cheddar cheese over the partially set eggs. Let stand for 1 minute, then gently fold to combine as the cheese melts.
08 - Transfer scramble to serving plates. Garnish with chopped chives or green onions if desired. Serve immediately.