01 -
Using a stand mixer fitted with a paddle attachment, combine butter, cream cheese, sugars, egg, and vanilla. Beat on medium-high speed until light and fluffy, about 5 minutes (7 minutes if using an electric hand mixer).
02 -
Stop the mixer, scrape down the sides of the bowl, then add flour, cornstarch, baking soda, and optional salt. Mix just until combined, about 1 minute.
03 -
Add chocolate chips and chunks, and mix briefly or fold by hand until evenly distributed.
04 -
Using a 2-inch cookie scoop, form 28 heaping dough mounds. Flatten slightly with your palm, place on a plate, cover with plastic wrap, and refrigerate for at least 2 hours or up to 5 days. Do not bake warm dough.
05 -
Preheat oven to 350°F (175°C). Line a baking sheet with a non-stick mat or spray lightly with cooking spray. Arrange chilled dough mounds 2 inches apart (about 8 mounds per sheet).
06 -
Bake dough for 8 to 9 minutes until edges are set and the center appears pale and glossy but slightly underdone. Remove from oven before 10 minutes to avoid overbaking.
07 -
Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack. Store airtight at room temperature for up to 1 week, freeze for 3 months, or refrigerate unused dough for up to 5 days.