Preheat your oven to a toasty 400 degrees.
In a large bowl, let's dance with cold butter, brown sugar, and sugar until they're a light and fluffy trio—about 4 minutes of mixing joy. Don't forget to scrape the bowl's edges.
Now, add eggs and vanilla, and let them join the party for another minute.
Time to fold in the flour, cornstarch, baking soda, and salt. Toss in the chocolate chips and a generous cup of chopped peanut butter cups. Save around 1/3 cup for the cookie crown.
Roll the dough into balls weighing 4 to 6 ounces each. Place these delectable orbs on a parchment paper-lined, light-colored baking sheet.
Slide them into the oven for 9-11 minutes. As soon as they emerge, delicately crown each cookie with the reserved peanut butter cups. Let them chill and set for 10 minutes.