I don’t think that you will need a whole different recipe to achieve a coffee flavored cake. There are several ways that you would be able to infuse a coffee flavor into the cake and into the filling and icing.
I would start with whatever cake recipe you have for the vanilla cake and instead of vanilla extract make extra-extra strong coffee and add in at the appropriate place. If you need a robust coffee flavor in the cake itself, I would recommend instant coffee with enough liquid mixed into it (you could use vanilla extract or water or brandy or bourbon or milk) to make a damp paste that would be added to the batter when you would have added vanilla extract. Alternately, you could use the instant coffee to flavor the liquid in the cake batter, milk or water. Here again you would want it strong. You could also just brew strong coffee from ground beans if your recipe calls for water or make a café au lait with the milk.
Or… make your vanilla cake and have the filling be coffee flavored, but add a simple syrup wash to the cake that is flavored with strong coffee.
As far as fillings, the first butter cream that I ever made that was the cooked sugar variety was a brown sugar butter cream and I paired it with a coffee flavored wash on the cake. It was quite yummy. I got the recipe out of either Gourmet or Bon Appetite, I don’t remember which one it has been at least seven or eight years (yikes, I’m getting old). However, I think I can find the recipe if you are interested.
You might want to be careful with the coffee flavoring. I love coffee, probably even more than the next guy, but coffee flavored cake with coffee flavored filling and coffee flavored icing might be a bit much. Which is why I recommended the brown sugar butter cream; it accents with out overpowering and also cuts the strong coffee flavor without changing it. Chocolate and coffee=mocha, an entirely different flavor, neither coffee nor chocolate. I don’t think you want that for the coffee flavored cake, you want distinct coffee. Unless the bride and groom like to drink black espresso, too much coffee flavor with out the equivalent of a little cream and sugar might not be what they had in mind. (Remember that coffee flavored ice cream is not a black coffee sorbet, it has cream and sugar in it.)
Are you doing a confectioner’s sugar icing, a cooked sugar butter cream and is fondant in the picture?
Hope all this helps.
