If using oven, preheat to 425°F.
To ensure even cooking, gently pound chicken breasts between 2 pieces of plastic wrap or waxed paper until they are of equal thickness throughout.
Dry thoroughly on paper towels.
Season melted butter with paprika, garlic or onion and salt and pepper.
Dip supremes in seasoned butter and sprinkle with lemon juice (this keeps them white).
Transfer to nonstick skillet large enough to accommodate them in a single layer.
Place buttered waxed paper or parchment over breasts and cover tightly with lid or foil.
Bake, or cook on stove top over medium-high heat, until opaque and springy to the touch, about 8 to 10 minutes; watch closely so they do not overcook (juices should run clear when meat is pierced).