1. Preheat oven to 350°F (175°C). Line two baking sheets with parchment paper.

2. Melt butter and chopped chocolate together until smooth. Let cool slightly.

3. Whisk brown sugar, granulated sugar, eggs, and vanilla into the chocolate mixture.

4. In a separate bowl whisk together flour, cocoa powder, baking powder, and salt.

5. Add dry ingredients to wet ingredients and mix until combined.

6. Scoop dough onto prepared baking sheets, spacing cookies 2 inches apart.

7. Bake for 10 to 12 minutes until the tops are set but centers remain soft.

8. Cool on the baking sheet for 5 minutes before transferring to a wire rack.

9. For the topping, combine evaporated milk, butter, brown sugar, and egg yolk in a saucepan over medium heat.

10. Cook while stirring until thickened, about 8 minutes.

11. Remove from heat and stir in vanilla, coconut, and pecans.

12. Allow topping to cool slightly, then spoon onto cooled cookies.

13. Let topping set before serving.