In a small bowl, lightly beat the eggs to break up the white and the yolk.
Over a medium heat, heat pan. Add butter and melt.
Once butter is melted, add eggs, stirring constantly just until eggs begin to set. Adjust heat if necessary, turning it to medium low if eggs cook too quickly.
Once eggs have begun to set, add cheese and any fillings in a row perpendicular to the handle of the pan.
Using the spatula, gently begin to roll the eggs away from you while tipping the pan down. Ideally the omelette will roll onto itself in thirds.
Roll onto plate and brush the top of the omelette with butter if desired.