1Preheat oven to 350 F. Grease 9x13 baking dish.
2Cook sausage over medium-high heat until browned and crumbly. Drain grease.
3Chop spinach and steam in the microwave for a few minutes.
4Beat eggs and sour cream together in a large bowl. Add sausage, cheddar cheese, spinach and oregano; pour into prepared baking dish.
5Bake for 30-40 minutes, or until a knife inserted in the center of the casserole comes out clean.