Preheat oven to 275 degrees. (Yes, that's right!)

Generously butter a cake tin and dust with cocoa.  

Sift together flour, baking soda and salt.

Heat coffee and liqueur or flavoring. Add chocolate and butter, stirring until melted. When smooth, add sugar and stir until dissolved.   Let mixture cool for several minutes and then transfer to large mixing bowl.  

Add flour mixture 1/2 cup at a time, beating until smooth after each addition.  

Add eggs and vanilla. Beat 1 more minute.

Pour into cake tin and bake 1 1/2 hours until cake pulls away from sides and springs back when touched in middle.    

Remove cake from oven and let it cool for 10 minutes in pan, then invert onto plate and leave tin sitting over it. Remove tin when cake is completely cool.