01 -
Set your oven to 350°F. Get some baking sheets ready by lining them with parchment paper.
02 -
Stir the flour, salt, baking soda, and baking powder together until they're evenly mixed.
03 -
Whip the butter and sugar together for around 2 minutes until it's fluffy and pale. Add the egg, yolk, and vanilla, and mix it in well.
04 -
Gradually add the dry mix to the wet mix. Keep your mixer on low and stop when they're just barely blended.
05 -
Form the dough into 1-inch balls. If you'd like, roll the balls in sugar. Space them around 3 inches apart on the baking sheets.
06 -
Cook one tray at a time for 8-9 minutes until the tops look just barely set. Be careful not to overcook them.