Make the Bat Wings

1. In the bowl of a food processor, pulse the flour, cocoa, sugar, salt, and baking soda to mix thoroughly.
2. Add the butter chunks and pulse several times.
3. Combine the milk and vanilla in a small pitcher. With the food processor running, pour in the milk mixture and continue to process until the mixture clumps around the blade or the sides of the bowl. Transfer the dough to a large bowl or a cutting board and knead a few times to ensure it is evenly blended.
4. Form the dough into a log about 12 inches long and 1 ½” inches in diameter. Wrap the log in clingfilm and refrigerate until firm (at least one hour or until needed).
5. Position racks in the upper and lower thirds of the oven and preheat the oven to 350°F—line rimmed baking sheets with parchment paper. Cut the log of dough into slices a scant ¼” inch thick. To make the wings, cut 12 rounds in half. Cut out two half-moons from the flat side of each semi-circle using a round cutter or the bottom of a piping tip. Place one inch apart on the lined sheets (cookies will spread). You can reshape the scraps or bake the round cutouts for snacking, and excess dough freezes well.
6. Bake, rotating the baking sheet from top to bottom and back to front about halfway through baking (12–15 minutes in total). The cookies will puff up and deflate; they are done about 90 seconds after they deflate.
7. Cool the cookies on the baking sheets or slide the parchment onto racks to cool completely.

Make the Cupcakes

1. Place cupcake liners in two 12-cavity cupcake pans, or if using a good quality baking spray, apply it just before filling the pans.
2. In a medium bowl, whisk together the cocoa and boiling water until smooth. Cool to room temperature. Tip: Place the bowl over a pan filled with ice water and stir occasionally. Make sure the bowl is secure and doesn’t tip.
3. In a medium bowl, beat the eggs lightly with ¼ of the cocoa mixture and the vanilla.
4. In the bowl of a stand mixer fitted with the paddle attachment, mix the rest of the dry ingredients on low speed until combined. Add the butter and the rest of the cocoa mixture. Mix on low speed until the ingredients are combined (30 seconds). Add the butter and the remaining cocoa mixture. Increase the speed to medium and beat until the mixture is thoroughly combined (1 1/2 minutes). Scrape down the sides.
5. Add the egg mixture in three batches, beating for 20 seconds after each addition. Then, scrape down the bowl once more.
6. Divide the batter among the prepared pans. Bake until a toothpick inserted in the centre comes out clean and the cake springs back when lightly touched (15–17 minutes).
7. Let the cupcakes cool in the pans for 5 minutes before removing them and letting them cool on wire racks.

Frost and Decorate the Cupcakes

1. In the bowl of a stand mixer fitted with the whisk attachment, beat the eggs, egg yolks and salt until pale and thick (4 minutes).
2. In a medium saucepan over medium-high heat, bring the sugar and 1/3 c of water to a boil. Continue to cook, swirling occasionally (not stirring), until the temperature reaches 248°F (firm ball stage).
3. With the mixer running, gradually pour the syrup into the egg mixture, where the eggs meet the sides of the bowl (avoid the beaters as much as possible, as they will cause the syrup to splash and thicken too quickly). Beat until the eggs are light and fluffy and the outside of the bowl is cool to the touch (5 minutes). Tip: Hold a bag of frozen vegetables outside of the bowl to bring the temperature down quickly.
4. One piece at a time beat in the butter. Make sure each piece is incorporated before adding the next. Take your time with this. If the mixture begins to look soupy or curdled, relax. It’ll come together. Just keep beating.
5. Beat in the chocolate and vanilla.
6. Apply the frosting to the cooled cupcakes using a plain round piping tip. Add the candy eyes and drop the cupcakes into spider web cupcake holders. Refrigerate the cupcakes so the icing can harden a bit before adding the Chocolate Wafer Bat Wings.