Set your oven to preheat at 325 degrees Fahrenheit and grease a 12-cup muffin tin with a neutral oil or line with silicone cups.
Place eggs, cottage cheese, garlic powder, black pepper, and kosher salt into a blender or food processor and blend until smooth, about 30 to 45 seconds.
Distribute the chopped baby spinach and shredded cheddar cheese evenly into the prepared muffin cups.
Pour the egg mixture into each muffin mold, filling nearly to the top.
Bake the muffins for 24 to 26 minutes or until the tops are lightly browned and a toothpick inserted comes out clean.
Allow the muffins to cool completely in the pan; they will shrink slightly as they cool.
Use a small silicone spatula to gently remove the muffins from the tin once fully cooled.