Whisk eggs, salt and pepper in a large bowl to blend. Melt two teaspoons butter in a nonstick skillet over medium heat. Ladle 3/4 cup of the egg mixture into the skillet. Cook until eggs are softly set, stirring often and lifting the edge of the eggs to allow the uncooked portion to run under, covering skillet if necessary to help set the top. Place 1/4 of the smoked fish on half of the omelet. Sprinkle with one tablespoon onion and top with two tablespoons cream cheese. Fold omelet in half and slide out onto a plate. Repeat with the remaining ingredients to make three more omelets.