For the cake

1. Preheat the oven to 350°F. Line the bottom of an 8-inch (20-cm) cake pan with parchment paper and grease the sides.
2. In a large mixer bowl, combine the flour, sugar, cocoa powder, baking soda and salt.
3. In a medium bowl, combine the hot coffee, milk, vegetable oil and vanilla extract. Add the egg and egg white and whisk until combined.
4. Pour the coffee mixture into the flour mixture and mix until smooth. The batter will be thin.
5. Pour the batter into the prepared cake pan and bake the cake for 30 to 35 minutes. To test the cake for doneness, insert a toothpick into the center of the cake. If the toothpick comes out clean, the cake is done.
6. Remove the cake from the oven and allow it to cool for 15-20 minutes, then remove the cake from the pan and transfer it to a cooling rack to cool completely.

For the ice cream:

1. Make the whipped cream: Place your mixing bowl in the freezer for 5-10 minutes to get it nice and cold. Prepare the whipping cream. Pour the heavy whipping cream into the chilled bowl and use an electric mixer to beat the heavy cream on medium-high speed until the cream reaches soft peaks. Add the powdered sugar and continue beating on high speed until peaks start to form. Set the whipped cream aside.
2. Beat the cream cheese and sugar in a large bowl until it’s completely smooth. Add the milk and vanilla extract and mix until well incorporated. Next, add the peanut butter and mix until it’s completely smooth.
3. Carefully fold about one-third of the whipped cream into the cream cheese mixture, then fold in the remaining whipped cream until the mixture smooth and combined. Gently stir in the chopped peanut butter cups.

To assemble the cake:

1. In an 8-inch cake pan,wrap the sides of the pan with saran wrap so it hangs over the top edge. Place a cake board in the bottom of the pan. 
2. Use a large serrated knife to remove the dome from the top of the cake so that it’s nice and flat. Set the chocolate cake in the bottom of the prepared pan then spread the ice cream in an even layer of top of the cake. Loosely cover the top of the cake and put it in the freezer until firm, 4-6 hours.
3. Once the cake is frozen, take it out of the freezer and use the clear plastic wrap to lift the cake out of the cake pan. Place the cake on a serving plate or on a cardboard cake circle. Use a warm offset spatula to smooth the sides, if needed.

For the chocolate ganache:

1. Place the chocolate chips in a small heat-proof bowl. Microwave the heavy whipping cream in a small, microwave-safe measuring cup until it comes to a boil.
2. Pour the hot cream over the chocolate chips and let them stand, covered, for about 5 minutes. Whisk the chocolate mixture until the chocolate is melted and the mixture is smooth.
3. Allow the ganache to cool for about 3 to 5 minutes. Then pour it over the top of the cake and allow it to drizzle down the sides.
4. Finish the cake with the chopped mini peanut butter cups piled on top. Place the cake back in the freezer until you are ready to serve. Remove from the freezer 15-30 minutes before serving for easier slicing.