Preheat your oven to 350°. Line a 12 hole muffin tin with liners and spray each liner with non-stick cooking spray (see recipe note). In a large bowl, whisk together eggs, milk, 1 tsp salt and ½ tsp pepper. Using a ¼ cup measuring cup, scoop ¼ cup of the egg mixture into each lined muffin hole. Each muffin hole will be about ⅔ full. Set aside.
In a large frying pan, cook the bacon until crisp. Place cooked bacon on paper towel lined plate to drain, set aside.
In the same frying pan, wipe out all but 1 tablespoon of the bacon fat (see recipe note). Add the diced potatoes and cook until they begin to brown and become tender, about 10 minutes.
Add the diced onion to the potatoes and cook until softened and beginning to brown, about 3-5 minutes. Remove the pan from the heat.
Scoop 1 tablespoon (see recipe note) of the mixture into each muffin hole. Add ½ piece of cooked bacon, crumbled, to each muffin hole. Then add a sprinkle of the shredded cheddar cheese (you should use the entire cup of cheddar and have no leftover cheese).
Carefully stir each egg bite to disperse the filling ingredients.
Place muffin tin in preheated 350° oven and bake for 15-20 minutes, until egg bites are puffed and golden brown.
Let cool for 5 minutes and serve. If freezing, let cool completely and store muffin lined egg bites in freezer safe resealable bag or container for up to two weeks. When reheating, place frozen egg bite in microwave and cook on high for one minute. Enjoy!°