1. Preheat Your Oven and Prepare Your Muffin Tin: Start by preheating your oven to 350 F (175 C). Lightly spray a 12-cup standard muffin tin with cooking spray. This step is crucial to prevent sticking and ensure easy removal of your egg muffins.

2. Combine the Wet Ingredients: In a large mixing bowl, whisk together the 12 large eggs, 1 cup of egg whites, 1/2 cup of cottage cheese, and 1/4 cup of milk until well combined and slightly frothy. The cottage cheese will break down as you whisk, creating a smooth mixture.

3. Stir in the Flavorful Add-ins: Add the 1/2 cup of shredded cheddar cheese, 1/4 cup of finely diced bell pepper, and the optional 1/4 cup of cooked ham or turkey bacon to the egg mixture. Season with 1/4 teaspoon of salt and 1/8 teaspoon of black pepper. Gently stir everything together until the ingredients are evenly distributed.

4. Fill the Muffin Tin: Carefully pour the egg mixture into each cup of the prepared muffin tin, filling each about three-quarters of the way full. Avoid overfilling, as the egg muffins will puff up slightly during baking.

5. Bake Until Set: Place the muffin tin in the preheated oven and bake for 20-25 minutes. The egg muffins are done when they are set in the center, lightly golden brown around the edges, and spring back when gently touched.

6. Cool and Serve: Once baked, remove the muffin tin from the oven and let the egg muffins cool in the tin for 5 minutes. This allows them to firm up slightly, making them easier to remove. Then, use a small spatula or knife to gently loosen and transfer them to a wire rack to cool completely, or serve warm.