1. Preheat oven to 375. Set six 6-ounce ramekins or custard cups on a baking sheet for easy handling. Heat 1 tablespoon butter in small nonstick skillet over medium heat. Add onions and cook until softened stirring occasionally, 8 to 10 minutes. Stir in parsley and 1/8 teaspoon each salt and pepper; remove from heat.
2. Layer half of the potatoes in the ramekins, dividing evenly; season with half the remaining salt and pepper. Top with half of the ham, onions and raclette cheese. Repeat with remaining ingredients. Bake until heated through, about 25 minutes.