For the Cookies:

1. Preheat and prepare pans:
   Preheat the oven to 350°F. Line baking sheets with parchment paper or silicone baking mats.
2. Mix dry ingredients:
   In a medium bowl, sift together the flour, cocoa powder, baking powder, and salt.
3. Cream butter and sugars:
   Using an electric mixer, beat the butter, brown sugar, and granulated sugar on medium-high speed until smooth and creamy.
4. Add wet ingredients:
   Beat in the egg, egg yolk, and vanilla extract until fully incorporated.
5. Combine wet and dry ingredients:
   On low speed, gradually add the dry ingredients to the wet mixture. Fold in the chocolate chips with a spatula.
6. Shape and bake:
   Using a medium cookie scoop, drop dough in 1 1/2-tablespoon rounds onto prepared baking sheets, spacing them about 2 inches apart.
   Bake for 10 minutes, or until the cookies are set. Let cool on the baking sheets for 10 minutes before transferring to wire racks to cool completely.

For the Topping:

1. Cook the mixture:
   In a small saucepan over medium heat, combine evaporated milk, sugar, egg yolk, and butter. Stir frequently until thickened, about 10 minutes.
2. Add coconut and pecans:
   Remove from heat and stir in vanilla, shredded coconut, and chopped pecans. Let cool until spreadable.
3. Assemble the cookies:
   Spread the coconut-pecan topping over each cooled cookie. Drizzle melted chocolate over the top.
4. Set and serve:
   Allow the cookies to set for at least 15 minutes. Serve and enjoy!