Preheat oven to 375°.
Place potato in a medium saucepan; cover with water. Bring to a boil; cook 4 minutes or until almost tender. Drain.
Cook bacon in a large nonstick skillet over medium heat until crisp. Remove bacon from pan, reserving 2 teaspoons drippings in pan. Crumble bacon; set aside. Add potato, onion, 1/4 teaspoon salt, and thyme to drippings in pan; cook 8 minutes or until potato is lightly brown over medium-high heat. Remove from heat; cool.
Combine the potato mixture, bacon, remaining 3/4 teaspoon salt, 2 tablespoons chives, cheese, pepper, egg whites, and eggs, stirring well with a whisk. Coat 36 mini muffin cups with cooking spray. Spoon about 1 tablespoon egg mixture into each muffin cup. Bake at 375° for 16 minutes or until lightly brown. Cool 5 minutes on a wire rack. Remove frittatas from muffin cups. Top each with 1/2 teaspoon sour cream and 1/2 teaspoon chives.
Prepare the frittatas a day ahead, chill, and reheat them just before serving. You can also freeze them for up to a month. Run a sharp knife around the edges of the muffin cups to loosen them from the pans. If you don't have a mini-muffin pan, you can cook the frittata in a 13 x 9-inch pan at 375° for 15 minutes and cut into 36 squares.
MyRecipes is working with Let's Move!, the Partnership for a Healthier America, and USDA's MyPlate to give anyone looking for healthier options access to a trove of recipes that will help them create healthy, tasty plates. For more information about creating a healthy plate, visit www.choosemyplate.gov.