Dark Chocolate Chunk and Peanut Butter Chip Chocolate Cookies

"If you think the world's most perfect food pairing is chocolate and peanut butter, you're in for a treat. The cookies combine chocolate and peanut butter, twice. There's dark chocolate chunks and cocoa powder, with peanut butter chips and peanut butter. They're soft and chewy chocolate cookies, more so than they are peanut butter cookies. They're dark, rich, and aren't overly sweet. Cornstarch helps keep the cookies soft and supple without turning cakey. Make sure not to overbake; dark cookies can fool you into thinking they're still under-done, but firm up considerably as they cool...."