Using a stand mixer with the paddle attachment or a handheld electric mixer, beat cream cheese on medium until smooth. Scrape down the sides and bottom of the bowl. Add the sugar and beat at medium speed until sugar is incorporated.
Add egg and beat on medium until completely smooth.
In a microwave-safe bowl, combine chocolate and heavy cream. With your microwave on medium power, heat for 30 seconds and stir. Repeat until mixture is smooth. Test your chocolate to make sure it is not too hot before you add it to the cream cheese mixture. If it is too warm to comfortably touch, set aside for a minute or two until it cools slightly.
Add slightly cooled chocolate to cream cheese mixture and beat until incorporated. Add sour cream, Kahlua, espresso, vanilla, and salt. Mix well, scraping the sides and bottom so no white streaks remain.
Divide mixture evenly between cupcake cups, filling just under 3/4 full. It should make exactly 12 cup pies.
Bake for 12-15 minutes until edges look set. Middles will still be a little jiggly, but will finish cooking as they cool.
Cool on the counter for 20 minutes before transferring to the refrigerator. Chill for at least an hour.