Let sit until yeast bubbles. Add egg and egg yolk, additional 1/3 cup of sugar, melted butter, vanilla and salt.
Place the buns on a parchment lined or well greased cookie sheet or jelly roll pan. If you want the buns to have soft sides, place close together (about 1 inch apart). If you would like the buns to have a pronounced edge, without touching another roll, place no more than three to a row, with about 2-3 inches in between buns, you will need two baking sheets for this.