Preheat oven to 350 degrees Fahrenheit
Wash and prepare spinach and cilantro
Brown sausage and drain fat
Heat butter and cream cheese together in microwave until partially melted, about 1 minute. Blend together with fork and set aside to cool.
Whisk eggs together in 4-quart bowl until evenly mixed.
Add cream cheese/butter mixture to eggs and mix well. Add white Cheddar cheese and stir till mixture is uniform.
In greased 9x13 pan layer half of the sausage, spinach leaves, and cilantro in that order, followed by a light sprinkle of Mozzarella cheese (be sure to save 1/3 cup for the top). Repeat to make another layer.
Once you've layered your ingredients, pour the egg mixture evenly over the top. The egg mixture will run down into the layers.
Cover the top with the remaining Mozzarella cheese and the walnuts.
Place in heated oven and bake uncovered for 20 minutes. Check internal temperature at this point. We consider egg dishes done when they reach 180 degrees internally. If you want a lightly browned top, bump oven temperature to 450 degrees at this point and cook for an additional 10 minutes