Preheat oven to 400° F. Spray cooking spray on two cookie sheets and set aside. In a standing mixer, mix together the butter, brown sugar, and white sugar on high until creamy (about 3-4 minutes). Halfway through mixing, scrape down the sides of the bowl to make sure it's completely mixed.
To a separate bowl, add the flour, cocoa powder, baking soda, cornstarch, and salt. Whisk together and set aside.
Add vanilla extract and eggs to the standing mixer, and mix on medium until well combined. Make sure to scrape down the sides of the bowl. Add flour mixture to the standing mixer and mix on the lowest setting until just combined. Add chocolate chips while flour is still mixing in–this minimizes the risk of overworking the cookie dough.
Roll the cookie dough into 12 large balls and spread out 6 on each pan. Press down on each cookie with two fingers to flatten slightly, otherwise they won't flatten enough while baking. Bake for 9-10 minutes, or until they start cracking on the edges.
Flatten cookies slightly more with a spatula if not flat enough to put on topping. You can also use a large round cookie cutter to perfectly round out the cookies. Just make sure that the cutter is larger than the cookie, and move in a circular motion on the pan around the cookie immediately after taking them out of the oven.
While the cookies are cooling, make the coconut topping. Start by heating a frying pan on medium heat. Add the coconut and the chopped pecans, and stir until the coconut starts to brown. Be careful not to burn it! You want the pecans and the coconut to be toasted for the topping. Set aside and allow to cool.
In a sauce pan, melt the butter on low heat. Once melted, whisk in the egg yolks, evaporated milk, salt, brown sugar, and white sugar. Keep on low heat, you don't want the egg yolks to cook before everything has been heated. Make sure to keep whisking together, and gradually increase temperature to medium-low heat. Cook for about 5 minutes after the liquid comes to a low boil, until it starts to thicken. Remove from heat and stir in vanilla extract. Mix in toasted pecans and coconut. Set aside and allow to cool completely.
Melt 1 cup of melting chocolate in the microwave. Stir after every 30 seconds to make sure it doesn't burn. Once melted (it should only take 1 minute), spread about a tablespoon on top of each cookie (make sure the cookies are completely cooled). Once you've allowed the chocolate to solidify, top each cookie with the pecan-coconut topping.
If you want, add a few whole pecans on top of each cookie for decoration. Enjoy!
