Preheat your oven to 350°F (175°C). Thoroughly grease a standard 12-cup muffin tin with non-stick cooking spray or butter. This step is crucial for easy removal.

Ensure the 6 slices of bacon have been cooked until very crispy, then blot away excess grease and crumble them into small, bite-sized pieces. Set aside for folding.

In a large mixing bowl, crack all 12 large eggs. Add the heavy cream (or milk), salt, and black pepper.

Whisk the mixture vigorously for 1-2 minutes until the eggs are fully uniform and slightly frothy on top. This aeration helps create a fluffier texture.

Gently fold the shredded cheddar cheese, the crumbled bacon pieces, and the optional chopped chives into the egg mixture. Ensure the solids are distributed evenly.

Carefully pour the egg mixture into each prepared muffin cup, aiming to fill them about three-quarters of the way full. Do not overfill, as they will puff up during baking.

Bake for 20 to 25 minutes (or until 30 minutes in the event your oven runs cool). The egg bites are done when they are set, puffy, lightly golden around the edges, and a toothpick inserted into the center comes out clean.

Remove the muffin tin from the oven and allow the egg bites to cool in the pan for 3 to 5 minutes. This cooling time allows them to settle and prevents them from sticking.

Use a small offset spatula or butter knife to gently loosen the edges, then carefully lift the egg bites out of the pan. Serve warm immediately or cool completely before storing for up to 4 days.