I think using Disaronno and almond extract in this cake would be delicious. Here’s what I’d suggest: swap out the champagne for the disoranno and the vanilla for the almond extract, using the same amounts of each. Then, taste the cake (after it’s cooled) to decide if you’d like a stronger almond flavor. If you do, simply brush more disoranno over the top of the cake, letting it soak in. To add disoranno to the icing, you won’t need to reduce it on the stovetop, like I suggest for the champagne. Simply beat it in, bit by bit, tasting and paying attention to the icing consistency until you get the flavor to the level of almond that you want. The goal is to get a strong enough almond flavor without adding so much that the icing gets too runny. Adding it a little at a time will allow you that level of control. You could also add a teaspoon or two of almond extract to the icing if you wanted to boost the almond flavor even more.