Preheat your oven to 350° F.
Chop your onion, spinach, and tomatoes.
Heat a large skillet over medium heat and add olive oil.
Once oil is heated, add in the sausage.
Cook sausage for about 3-5 minutes, until cooked completely.
Add in the chopped vegetables. Stir frequently.
Add in the salt, onion powder, garlic powder, and chili powder. Stir to evenly distribute.
Once cooked, set aside to cool for a few minutes.
Line your muffin tins with muffin tin liners or spray them with cooking spray.
Spoon in some of the vegetable and sausage mixture. Be sure to not overfill them no more than halfway.
In a large bowl, scramble 12 eggs. Mix in 3-4 tablespoons of water to make them fluffier.
Carefully add the eggs to the muffin tins. Be sure to not overfill them, but they will be fine if they are filled close to the brim.
Bake the egg cups for 15-20 minutes or until no liquid is visible and a fork can be inserted and removed with no liquid mixture visible on the fork or in the cup.