01 -
Using a stand mixer (5 mins) or hand mixer (7 mins), whip butter, cream cheese, sugars, egg, and vanilla till fluffy and pale.
02 -
Slowly stir in flour, baking soda, cornstarch, and salt. Mix just until blended, around a minute.
03 -
Gently stir in chocolate chunks or chips until evenly scattered through the dough.
04 -
Portion dough into 2-inch balls. Gently press the tops, then chill in the fridge for a minimum of 2 hours or as long as 5 days.
05 -
Cook in the oven at 350°F for 8-9 minutes. Sides should firm up, but centers can stay a little soft. Leave them on the tray for 5 minutes before moving.