Get all of the ingredients from above so you can get started!
Preheat oven to 350F. Grease a muffin tin. Set aside.
Separate 8 egg yolks from their egg whites. Discard the yolks and add the whites to a large bowl. Add 4 additional whole eggs and greek yogurt. Whisk until smooth.
Add cheddar, mushrooms, and spinach. Stir to combine.
Divide mixture between 8 muffin tins. Transfer to oven and bake 22-25 minutes, until golden and set.
Cool slightly then carefully remove from muffin tin.
Add a serving to a small plate and enjoy!
Serving Size 2 egg cups
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.