Preheat oven to 375°F (190°C). Line Cookie Sheet with Parchment Paper. Combine flour, cocoa powder, baking powder and baking soda in Mixing Bowl. Combine butter, sugar, egg yolks and vanilla in Mixing Bowl; beat on medium-high speed of electric mixer until well blended. On low speed, add flour mixture in three additions, alternating with milk in two additions; mix well.
Using level Small Scoop, scoop batter onto prepared Cookie Sheet 2 in. (5 cm) apart; bake 7-9 minutes or until cookies spring back when lightly pressed. Slide parchment and cookies onto Cooling Rack; cool completely. Repeat with remaining batter.
For filling, combine sugar and salt in (2-qt./1.9-L) Saucepan. Gradually whisk in evaporated milk, egg yolks and vanilla using Silicone Sauce Whisk. Add butter; cook over medium heat, stirring constantly, 8-10 minutes or until temperature reaches 160°F (71°C). Pour into Classic Batter Bowl. Add coconut and pecans; mix well. Refrigerate 1 hour or until cool. Meanwhile, prepare Ganache.
To assemble, turn cookies bottom side up. Using slightly scant Medium Scoop, scoop filling onto half of the cookies, pressing down slightly so filling spreads almost to the edge. Spoon 1 tsp (5 mL) ganache on remaining half of cookies. Place one filled cookie on top of ganache, pressing slightly. Garnish, if desired.