Beat egg in a bowl and add some panko bread crumbs in another. Heat skillet to medium high. Add olive oil. Dip one side of bread in egg, then bread crumbs, then place that side down in pan. Add cheese and tomato. DO the same with the other slice of bread place egg and bread crumb side up on top of sandwich. Flip and brown. When both sides are brown the sandwich is done. I used olive oil with this sandwich instead of butter because of the egg and bread crumb mixture.