In a medium bowl, combine the all-purpose flour, cornstarch, baking soda, salt, and cinnamon. Set aside.

In the bowl of a stand mixer fitted with a paddle attachment, add the brown sugar and granulated sugar.

With the mixer on low speed, slowly drizzle in the melted and cooled butter until fully incorporated.

While the mixer is running, add the whole egg, egg yolk, and vanilla extract, allowing each to incorporate before adding the next.

Add the flour mixture in three additions, mixing each until incorporated.

Stop the mixer and add the chocolate chips, oats, pecans, and coconut. Mix on low speed until evenly distributed.

Cover the bowl with plastic wrap and refrigerate for 30-45 minutes.

Preheat the oven to 350F and line a baking sheet with parchment paper.

Scoop out dough using a 2-inch cookie scoop and place 6 to 8 dough balls on the baking sheet, lightly pressing down on them.

Bake for 11-13 minutes, or until lightly browned and set.

Allow cookies to cool on the sheet for 3-5 minutes before transferring to a cooling rack.