Preheat your oven to 350°F. Spray a mini muffin tin with cooking spray.
In a bowl, whisk together the eggs and milk until well combined.
Divide the shredded cheese, diced vegetables, and any other optional ingredients among the muffin cups.
Pour the whisked egg mixture over the fillings in each muffin cup, filling them almost to the top.
Bake in the preheated oven for about 15-18 minutes, or until the egg bites are set and slightly golden on top. The cooking time may vary, so keep an eye on them.
Allow the mini egg bites to cool for a few minutes before using a knife to loosen the edges and pop them out of the muffin tin.