Marsala is a sweet fortified wine. While it should be readily available, if you aren’t able to get hold of any, I found that cream sherry made a good substitution. If you can’t find authentic savoiardi biscuits then ladyfinger sponge biscuits will make a good substitution. I used both these alternatives one Easter Monday, when I had my family offer for lunch, and everyone really loved it. I couldn't believe how good it tasted and it was even better the next day.