Melt butter in a cooking pot or pan. Pour the egg yolk mixture into the pan.
Continue to cook until the consistency becomes very thick to the point that it can easily form a shape when moulded.
Transfer the mixture to a bowl. Let it cool down.
Cut the cellophane into 3x3 inch pieces. Scoop 1 tablespoons of mixture and place at the middle of the cellophane. Wrap the yema while moulding to form a pyramid shape piece (note: watch the video for details).
Continue to wrap the yema until all the mixture is consumed.