Best place to grab takeaway lunch at Milan Centrale?

There is a book store/snack store right near the entrance into the loading gates at Milan Central, as you enter the store there are coolers on the left side with sandwiches, chips, etc. We have been through this station many times and have bought food here for the train, actually the sandwiches are pretty good. Right in front of the store is the big sign with all the departures and which track it will be on. Hope this helps!

There is no shortage of places to "grab and go" a sandwich or other lunch items.

https://www.milanocentrale.it/en/store/index/food

The question is which, so you don't waste time looking around. If there were a Princi, that would be my choice, but there isn't. But since Princi and Starbucks are now partners of a sort, perhaps they have Princi focaccia and other items at the Starbucks.