In large skillet, cook hash browns in butter over medium-high, stirring occasionally, until golden and dry, 8 to 10 minutes. Sprinkle with paprika; season. Coat 8 muffin cups with cooking spray; add hash browns, pressing bottom and sides to form nests. Spray with cooking spray. Broil until starting to crisp, 5 to 8 minutes. Add ham and cheese. Crack 1 egg into each cup. Top with pimientos; season. Bake at 350° until whites are set, about 10 minutes; season. Top with scallions.