1. Heat oven to 350° with rack in the center. Lightly coat a 12-cup Bundt pan with baking spray; set aside.
2. To make cake: Combine flour, baking powder, salt, and cocoa powder in a medium bowl, whisking well; set aside. Place butter in a separate bowl; beat with an electric mixer at medium-low speed, until soft and creamy. Add sugar; beat well. Add eggs one at a time, beating well after each addition. Gradually beat in flour mixture, alternating with sour cream first, then coffee. Stir well with rubber spatula; scrape any batter at the bottom to combine.
3. Spoon batter into prepared pan, spreading evenly. Bake until knife tip inserted in the middle comes out clean (45-55 minutes); let cool.
4. To make sugared coffee beans: Sprinkle some superfine sugar onto a sheet of wax paper. Dip 1 coffee bean into honey, transfer wet bean to wax paper, and sprinkle with superfine sugar. Continue with the remaining coffee beans; let dry.
5. To make glaze: Combine powdered sugar, espresso powder mixture, and liqueur (if desired) in a medium bowl; stir well with a fork until smooth. Transfer cooled cake to a serving platter. Drizzle glaze generously over cake; decorate with sugared coffee beans.