Preheat the oven to 350 degrees. Butter and flour a 12-cup Bundt pan. In a small bowl, mix together the sugar, instant coffee, and cocoa. Separately whisk together the flour, baking soda, baking powder, and salt. Using an electric mixer, cream together the butter and sugar. Add one egg at a time, beating until just combined. Beat in one third of the flour mixture, then half of the sour cream, then another third of the flour mixture. Beat in the remainder of the sour cream and the last third of the flour mixture. Add the vanilla and mix for another minute or two, scraping the sides of the bowl well with a spatula.

Pour one third of the batter into the prepared pan and sprinkle half of the filling on top. Pour in another third of the batter and sprinkle the remainder of the filling on top of that. End with the last third of the batter. Run a dinner knife down through the batter and swirl the knife gently to marble the batter.

Bake for 45-50 minutes, or until a cake tester inserted in the middle of the cake comes out clean. Cool on a rack for 30 minutes, then turn out onto a plate or onto foil. The cake can be frozen while still warm.

Source: adapted from Martha Stewart