Preheat oven to 275° F. Butter a 9" tube pan and dust the bottom and sides with cocoa powder.
Heat coffee and bourbon in a heavy saucepan over low heat. Add chocolate and butter and stir until smooth. Remove from heat.
Add the sugar to the chocolate mixture and let cool for 5 minutes.
Stir flour with baking soda and salt. Add to the chocolate mixture in thirds, stirring well between additions.
Add eggs and vanilla, and stir until smooth. Pour into pan.
Bake approximately 1-1/2 hours. Cool completely before unmolding.
To unmold:
Run a knife around the edge of the cake, set a plate over the pan, and invert the cake onto the plate. Then, set another plate on top of the cake and flip the cake onto the plate. Its top should be upright.
Notes
Store leftovers in the refrigerator.Substitute equal amounts of coffee for bourbon if you would like to omit the liquor.