Beat the egg yolks and mix in the melted butter and set aside. In a standing mixer, add the egg white and sprinkle cream of tartar and beat it to stiff peak stage (#1). Fold in the egg yolk mixture until no white steaks are visible (#2). Melt the reaming butter in a 8 inch non-stick frying pan on medium heat until foam forms and add in the egg mixture and add topping and cheeses (#3). Place the pan into the pre-heated 375F oven (#4) and bake for 5 minutes (We did not use pasteurized eggs and wanted it to be completely cooked). If it springs back when lightly pressed it is complete done (#5). Tip the omelet onto the cutting board and let it rest for 30 seconds before cutting (#6).