Panera Bread Chocolate Chipper Cookies

Whisk together the flour, cornstarch, baking soda, and salt until blended.
Pour the melted butter into the bowl of a stand mixer, add the two sugars, and beat with the paddle attachment on medium speed until well combined.
Add the eggs and vanilla along with a couple large spoonfuls of the flour mixture, then beat until blended.
Add the remaining flour mixture in two additions, mixing on low speed between each addition until the flour is incorporated. Be careful not to overbeat, or the cookies will be tough.
Add the semisweet chocolate chunks and the finely chopped milk chocolate, stirring on low speed until the chocolate is evenly distributed throughout the dough.
Drop the dough in 3 tablespoon-sized scoops on 11x17-inch cookie sheets that have been lined with parchment paper. Place four balls of dough on each tray, spacing them far apart, and flatten them slightly to encourage them to spread.
Bake at 350°F for 14 minutes per tray, or until the edges of the cookies are golden brown.
Let the cookies cool for 8 minutes on the tray before transferring to wire racks to finish cooling. This allows them to finish cooking in the middle and will prevent them from breaking when you remove them from the trays.