Step 1: Make the Chocolate Cookies

1. Preheat your oven to 375°F (190°C). Line baking sheets with parchment paper.
2. In a medium bowl, sift together the flour, cocoa powder, baking powder, and baking soda.
3. In a large bowl, cream the butter and sugar until light and fluffy. Add the egg yolks and vanilla, mixing until well combined.
4. Gradually add the dry ingredients to the wet ingredients, alternating with the milk. Mix until just combined.
5. Using a small ice cream scoop or tablespoon, drop rounded portions of dough onto the prepared baking sheets, spacing them about 2 inches apart.
6. Bake for 8-10 minutes, or until the cookies spring back when lightly touched. Let them cool on the baking sheets for 5 minutes, then transfer to a cooling rack to cool completely19.

Step 2: Prepare the Coconut-Pecan Filling

1. In a saucepan, combine the sugar, evaporated milk, egg yolks, and butter. Cook over medium heat, stirring constantly, until the mixture thickens and reaches 160°F (71°C).
2. Remove from heat and stir in the coconut, pecans, and vanilla. Let the filling cool completely, then refrigerate for 1 hour to firm up910.

Step 3: Assemble the Whoopie Pies

1. Turn half of the cookies flat side up. Spread a generous tablespoon of the coconut-pecan filling on each.
2. If desired, drizzle a teaspoon of chocolate ganache on the remaining cookies.
3. Sandwich the cookies together, pressing gently to spread the filling to the edges.

Tips from Chef Robert Thomas

• Use High-Quality Cocoa Powder: For the best flavor, opt for dark unsweetened cocoa powder.
• Toast the Pecans: Toasting the pecans enhances their nutty flavor. Simply bake them at 350°F for 5-7 minutes.
• Storage: Store the whoopie pies in an airtight container at room temperature for up to 2 days or in the refrigerator for up to 1 week.