Preheat oven to 325F, grease a 12-muffin pan and set aside.
Heat nonstick pan or skillet on a medium heat. Once hot, add the olive oil, grated potatoes and cook for 3-5 minutes, or until potatoes are tender.
Add the raw sausage and cook until there is no pink in the meat. Add the spinach and cook for additional 2minutes. Season with salt and pepper and take it off the heat. Allow the spinach mixture to cool down a bit before using.
In a separate large bowl, crack and whisk the eggs until the white and egg yolk are well mixed. Add the cooked spinach mixture to the egg mixture and stir together. Pour them into the greased muffin pans and bake in the preheated oven for about 18-25minutes or until the muffins have risen and the tops are set and firm to touch.
Bring them out of the oven and allow to cool in the pans for about 5 minutes. Transfer the muffins to a cooling rack to cool completely. Serve and enjoy
Store leftover egg muffins in an airtight container and keep it in the refrigerator for about a week.