Preheat the oven to 400 degrees. Bake the potato for about one hour or until tender. Remove the inside flesh to a bowl, crumble it slightly with a fork and set it aside to let cool slightly (or let the potato cool, peel and chop the insides). Lower the oven heat to 375 degrees. Beat the eggs and milk together, stir in the parsley and sprinkle in some salt and pepper. Set aside. Heat the butter in a sauté pan over medium heat. When the butter has melted and looks foamy, add the onion and cook for 2 minutes or until it has softened. Add the potato and cook for about 5 minutes or until the pieces are lightly crispy, stirring occasionally. Add the spinach and cook for another minute, stirring occasionally. Pour in the eggs and turn the heat to low. Scatter the cheese on top. Stir once or twice, then cook undisturbed for 8-10 minutes, or until the bottom has set. Place the pan in the oven and bake for 8-10 minutes, until the eggs are set.
Ronnie Fein is a cookbook author, food writer and cooking teacher in Stamford. She is the author of The Modern Kosher Kitchen and Hip Kosher. Visit her food blog, Kitchen Vignettes, at www.ronniefein.com, friend on Facebook at RonnieVailFein, Twitter at @RonnieVFein, Instagram at @RonnieVFein.