In a bowl of a stand size mixer fitted with the paddle attachment, cream together the cold, sliced butter, dark brown sugar, and granulated sugar until well combined. About 3-4 minutes. This part is really important. This is what gives your cookie structure. Under mixing can result in a flat cookie.
With a rubber spatula, scrape down the sides and the bottom of the bowl. Add the egg, mix for 30 seconds. Then add the egg yolk, mix again, and the vanilla extract. Mix until the batter is smooth and creamy. Scrape the bottom and the sides of the bowl.
Add the all purpose flour, bread flour, baking powder, baking soda, cornstarch, kosher salt, shredded coconut, chocolate chips, and caramel bits, all at once and mix on low until combined, and the dough starts pulling from the sides of the bowl.
Weigh or scoop the cookie dough into portions, each weighing around 5.5 ounces. Add .5 ounces (roughly) of extra chocolate chips and caramel bits to the top of the dough. This is what gives it a caramelized finished look.
Chill the cookie dough in the refrigerator for about 30 minutes.
Preheat your oven to 410 and line a baking sheet with parchment paper.
After chilling, place each portioned out dough on the prepared baking sheet.
Bake for 8 -10 minutes. The top should look golden brown.
Let the cookies sit for 5-10 minutes before serving.