Preheat oven to 350 degrees F (175 degrees C).
Whisk both amounts of flour, baking soda and salt
in a bowl. Beat butter, brown sugar, and pudding
mix in another bowl with an electric mixer until
blended; beat in egg, egg yolk, and vanilla
extract until combined. Stir flour mixture into
egg mixture until just combined. Fold in chocolate
Roll the dough into 2-inch balls and place 2
inches apart onto ungreased baking sheets.
Bake until golden brown, about 15 minutes.