Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper and set aside.

In a large bowl, sift the 1 box devil’s food cake mix to remove any lumps.

Add 2 eggs, ½ cup unsalted butter (melted and cooled slightly), 1 tablespoon brown sugar, and 2 teaspoons vanilla extract to the sifted cake mix. Whisk or stir until the mixture is evenly combined into a uniform dough.

Using a 1 ½ teaspoon scoop or measuring spoon, portion the dough into mounds on the prepared baking sheets, placing them about 2 inches apart. Gently pat each mound to slightly flatten so the cookies do not bake too tall.

Bake the cookies for 7–12 minutes, depending on how fudgy or cakey you prefer them. Remove from the oven and let the cookies cool on the baking sheet for 2 minutes, then transfer to a wire rack to cool completely before filling.

While the cookies cool, make the filling: in a medium bowl, beat 4 ounces softened cream cheese and ¼ cup softened unsalted butter with a hand mixer for about 2 minutes until smooth and combined. Add 1 ½ teaspoons coconut extract and mix to incorporate.

Gradually add 3–4 cups powdered sugar to the cream cheese mixture, about 1 cup at a time, mixing after each addition until you reach a spreadable frosting consistency. Adjust within the 3–4 cup range to get your desired thickness.

Assemble the whoopie pies by matching cookies of similar size. Spread a layer of filling on the flat side of one cookie, then top with a second cookie flat side down, pressing gently so the filling reaches the edges.

Roll the exposed filling edges in shredded coconut for decoration. Chill the assembled whoopie pies briefly if you prefer the filling to be firmer before serving.