Preparation: Preheat your oven to 375 degrees Fahrenheit (190 degrees Celsius). Lightly grease a 6-cup muffin tin with cooking spray or a dab of oil.
Cook the Fillings: In a medium skillet over medium-high heat, cook the chopped bacon and diced red bell pepper until the bacon is crispy. Remove from heat and drain the excess grease.
Mix the Egg Base: In a large mixing bowl, whisk together the eggs, milk, mustard powder, salt, and pepper until well combined.
Combine Ingredients: Stir the cooked bacon and bell pepper into the egg mixture. Add the shredded cheddar cheese and chives, mixing until evenly distributed.
Bake: Evenly divide the mixture among the prepared muffin cups. Place in the oven and bake for 15-17 minutes, or until the muffins are set and slightly puffed up.
Serve: Let the muffins cool slightly before removing them from the tin. Serve warm.
