Melt the butter and stir in sugars.
Add egg, yolk and vanilla.
Add all the dry ingredients and stir just until blended.
Stir in the chocolate chips (they are tricky to stick) and chill till cold.
Preheat oven to 325 F. Line baking sheets with parchment paper.
Weigh out 2 ounce mounds and bake 16-18 mins.
Use a biscuit ring to swing them around when done for a perfectly round shape.