Created by Michelle_Minicucci on January 3, 2012
Step 1: Heat oven to 350°. Saute 1 1/2 cups diced onions in 1 tablespoon butter until soft and translucent.
Step 2: Add second tablespoon of butter to pan, and throw in diced ham and garlic. Saute until you like how brown it is. I like my onions and ham a little crispy in this dish, but it's not necessary.
Step 3: Set the pan to the side to cool down while you mix the other ingredients. In a small bowl, whisk together egg white, mustard, horseradish and yogurt.
Step 4: In a large bowl, combine mashed potatoes with 2/3 of sliced scallions, one cup of Manchego shredded cheese and yogurt mixture. (Reserve 1/3 of scallions and 1/4 cup of cheese for garnish.)
Step 5: When onions and ham have cooled a bit, fold into mashed potato mixture. If potatoes seem too dry, add milk 2 tablespoons at a time until smooth and creamy.
Step 6: Spray a 1 1/2 quart casserole dish with non-stick cooking spray and spoon mixture into dish. Cover with lid or foil.
Step 7: Cook at 350° for 45 minutes, or until heated through and cheese has melted. Uncover last 15 minutes and sprinkle last 1/4 cup of shredded cheese on top.
Step 8: Garnish with reserved scallions and chopped bacon or plain yogurt (sour cream) if desired.