Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
In a large bowl, combine brownie mix, flour, oil, and eggs until well blended.
Fold in chocolate chips.
Scoop tablespoon-sized balls onto prepared baking sheets.
Bake 9-11 minutes until edges are set. Cool completely.
In a saucepan over medium heat, whisk evaporated milk, sugar, egg yolk, and butter until thickened (5-7 minutes).
Remove from heat and stir in vanilla, coconut, and pecans.
Spread frosting over cooled cookies and let set before serving.