Preheat oven to 375° degrees and line a baking sheet with silicone mats or parchment paper and set aside.
Melt the butter and allow to cool.
Crush pecans (if you have whole pecans) by placing them in a Ziploc bag and smashing them with a rolling pin or something that will crush the pecans into smaller pieces.
In a separate bowl, whisk together flour, cornstarch, baking soda, salt, and cinnamon. Set aside.
In a large bowl, beat together melted and cooled butter, granulated sugar, and brown sugar on high for about 30-60 seconds.
Add in the eggs and vanilla and continue beating with an electric mixer until the wet ingredients are fully mixed and cohesive.
In small amounts, about ½ cup at a time, add in the dry ingredients and beat on low between each addition. Once the flour mixture is completely incorporated stop mixing.
Stir in the dark chocolate chips and 1 cup of crushed pecans.
Scoop cookie dough balls (about 50g) onto the cookie sheet, ensuring the dough balls are at least 2 inches apart. Sprinkle the remaining pecans on the top of the unbaked cookies.
Bake time for cookies is 9-11 minutes or until the bottom edges are golden brown and the top is slightly doughy.
Allow to cool on the tray for 5-10 minutes and remove with a spatula, placing them on a wire rack to fully cool.