Death by Chocolate Cupcakes

Preheat the oven to 350℉. Line a cupcake pan with 12 cupcake liners.
In a medium bowl, stir together the semisweet chocolate chips, black cocoa powder, and boiling water. Mix until the chocolate is melted. Set aside to cool.
In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking soda, and salt. Add the cooled chocolate mixture and whisk until combined. Add in the vegetable oil, eggs, and vanilla extract and whisk until the cupcake batter is combined and smooth.
Portion the cupcake batter into the cupcake liners. Bake the cupcakes for about 20 minutes until the tops of the cupcakes spring back when gently touched. Cool the cupcakes in the pan for 5 minutes and then transfer to a wire rack to cool completely.

In a microwave-safe bowl, heat the semisweet chocolate in the microwave in 15 second intervals, stirring in between each interval, until the chocolate is melted and smooth. Set aside to cool.
In a small mixing bowl, stir together the black cocoa powder and hot water until combined and smooth. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment or in a large mixing bowl with an electric hand mixer, whip the unsalted butter for 5 minutes until light, pale, and fluffy. Add in the powdered sugar, corn syrup, vanilla extract, and salt. Mix on low speed until well combined. Turn the speed of the mixer to medium speed and whip the frosting for 2 minutes.
Add in the cooled melted chocolate and black cocoa mixture, and mix on low speed until smooth. Scrape the sides and bottom of the bowl as needed. Turn the mixer to medium-low speed and mix the frosting for 2 to 3 minutes until it is smooth and creamy.

Add the heavy cream and ¼ cup milk to a small saucepan and place over medium heat. Heat the cream while working on the next step. In a medium mixing bowl, whisk together the granulated sugar, dark cocoa powder, cornstarch, egg yolk, and the remaining ¼ cup milk until smooth.
Once the cream mixture starts bubbling at the edges of the saucepan, remove the saucepan from the heat. Very slowly drizzle the hot cream into the egg mixture, whisking constantly. Be sure to drizzle slowly and whisk quickly to temper the egg mixture so it does not turn into scrambled eggs.
Once all the hot cream has been added to the egg mixture, pour the custard mixture back into the saucepan and place on the stove over medium-low heat. Whisk constantly until the mixture thickens and is bubbling about 3-5 minutes. Remove the saucepan from the heat.
Add in the semisweet chocolate, salted butter and vanilla extract and whisk until the chocolate and butter are melted and the pastry cream is smooth. If lumpy, pour the pastry cream into a fine mesh strainer over a large bowl. Use the back of a spoon to push through the pastry cream to remove any lumps. Place a piece of plastic wrap directly on top of the pastry cream to prevent a skin from forming. Chill for at least 6 hours before using.

Core the cupcakes to remove the center. Fill a piping bag with the tip cut off with the chocolate pastry cream. Fill the center of the cupcakes with the pastry cream. Fill a piping bag fitted with a Wilton 1M piping tip with the dark chocolate frosting. Pipe a generous swirl of frosting onto the cupcakes. Sprinkle the cupcakes with finely crushed chocolate sandwich cookies if desired.

Store the cupcakes in an airtight container in the refrigerator for up to 5 days. Serve at room temperature for the best taste and texture.

Metric conversions are calculated automatically. I cannot guarantee the accuracy of this information.