Preheat oven to 325 degrees F (165 degrees C). Pierce potatoes with a fork. Wrap in a sheet of aluminum foil.
Bake in the preheated oven until tender when pierced with a fork, about 1 hour.
Mix sour cream and cream cheese together in a bowl.
Slice the baked potatoes in half. Divide butter evenly over potatoes. Spoon the sour cream mix inside. Sprinkle green onions on top. Season with salt and pepper. Top with lox and caviar.
