01 - Preheat the oven to 350°F. Grease a 12-cup muffin tin with nonstick spray or a small amount of oil.
02 - In a large mixing bowl, whisk together the eggs, milk (if using), salt, black pepper, and smoked paprika until fully blended.
03 - Evenly divide the diced bell pepper, chopped spinach, diced tomato, spring onions, and optional ham or bacon across the muffin cups.
04 - Pour the egg mixture evenly into each muffin cup, filling them about three-quarters full.
05 - Sprinkle shredded cheddar cheese over the top of each filled muffin cup.
06 - Bake in the preheated oven for 18 to 22 minutes, or until the egg cups are set and lightly golden on top.
07 - Allow the egg cups to cool for 2 to 3 minutes before removing them from the tin. Serve warm or at room temperature.