You don't want the customer to get drunk!!!
Also, the flavor should be diluted to give a mellow suggestion of alcohol. An undernote if you will.
Alcohol, something tells me, may break down the tender structure of your cake if not the cream filling.
When flavoring syrups, you want to have enough alcohol to smell and taste without falling over.
I like to use 70% syrup 30% alcohol or coffee. For flavor pastes and oils, measurments vary.
bake first, ask questions later.Oooh food, my favorite!Professor Pastry Artswww.collin.edu