Preheat oven to 350 degrees Fahrenheit. Place nine 4” shallow paper baking cups on a large baking sheet. (They don't have to be exactly 4", but at least 3".)
In a bowl of a stand mixer fitted with a paddle attachment, beat butter and sugars on medium-high speed until fluffy, about 3 minutes.
Add eggs and vanilla and mix until combined.
In a medium bowl, whisk flour, cornstarch, baking powder and salt until well incorporated. Slowly add the dry ingredients to the mixing bowl with the wet ingredients, beating on low speed, until it resembles a soft cookie bater.
Add chocolate chips and ½ of the chocolate chunks until evenly distributed without overmixing.
Using a large spoon or ice cream scoop, add ½ cup of dough into each baking cup, gently pressing dough into the bottom of each one.
Sprinkle the remaining chocolate chunks on top of each cookie cup and gently press them into the top of the cookie.
Place the cookies in the oven and bake for 20 to 22 minutes until they are golden brown on top. The cookies will be brown on the outside edges and soft in the middle. Remove from the oven and let cool for 5 minutes before transferring them to a wire rack to cool completely.
Notes
These cookies are huge and can easily serve 2 people. Storing: Homemade cookie cups can be stored outside of the fridge in an airtight container for 4-5 days. A cake holder with a dome lid is best to keep the cookies from drying out.Freezing: To freeze these individual deep dish chocolate chip cookies, cool completely, then individually wrap each in plastic wrap before transferring to an airtight container or freezer-safe bag. Cookies will stay fresh for up to 4 months and can be thawed on the countertop.