Add the chopped dark chocolate, butter, and Kahlua into a bowl. In a double boiler over medium heat, melt together the mixture. (This can also be done in a microwave in 30-second intervals). Mix in the salt and vanilla and set aside to cool slightly.

In a stand mixer or with a hand mixer, add the egg whites and whisk together on medium speed until just foamy. After the egg whites are foamy, add in the sugar and whip until medium peaks form.

In a stand mixer or with a hand mixer, add the egg whites and whisk together on medium speed until just foamy. After the egg whites are foamy, add in the sugar and whip until medium peaks form.

Add the gelatin to the water. Mix to combine and set aside to bloom for at least 5 minutes.

While the gelatin is blooming, whip the egg yolks in a bowl with a hand mixer or the base of a stand mixer until they are pale in color. Fold the whipped egg yolks into the chocolate mixture.

After the yolks are added, heat ¼ cup of heavy cream in the microwave until warm but not boiling. Add the gelatin-water mixture to the warmed cream and mix to combine. Fold the mixture into the chocolate mixture.

After the gelatin is added, fold the whipped egg whites into the chocolate mixture

Lastly, whip the remaining ½ cup of heavy whipping cream until soft peaks form. Fold the whipped cream into the chocolate mixture until combined.

Pour the mousse into a bowl to set up before adding it into the cupcakes. Set for at least 4 hours in the fridge or overnight

Combine the sugar, flour, cocoa powder, baking soda, baking powder, and salt into a bowl. Stir together with a whisk until evenly combined

Add the vanilla, eggs, buttermilk, and oil and stir until combined

Once combined, add the hot coffee. Stir quickly to ensure the hot coffee is evenly distributed. The batter will be very thin

Pour the batter into a cupcake pan with liners and cook for ~20 minutes on 350 F – make sure a toothpick comes out clean

Set aside to cool

To make the ganache, add chocolate, butter, salt, and vanilla into a bowl. Set aside.

In a small pan over medium heat, heat cream and sugar until hot but just before boiling

Pour the heated cream and sugar over the bowl of chocolate and let it set for 1 minute. Stir until smooth

Set in the fridge until cooled but not hard. Stirring every 20 minutes. After about 1 hour it should reach an icing consistency but may take longer depending on the temperature of the fridge.

Once everything is cooled, cut a ½” core out of each cupcake. Fill with a scoop of chocolate mousse, pressing down with a spoon as needed. Top with chocolate ganache icing

Repeat with the remaining cupcakes