The square in Pollensa town is one of my favourite places. I just love the atmosphere on busy summer evenings.
Can I suggest one that is not in the main square though? Sa Trencadora on Carrer de Raymond Llull?
Link to Streetview here;
http://goo.gl/maps/oxsoO
Traditional Italian restaurant that has a lovely garden, just two minutes walk off the main square. It gets busy with locals and visitors, so well worth calling in or sending an email to reserve a table outside. There have been some great reviews on here too.
I would suggest dining there, and then walking to the square for post-meal drinks.
If you are still hungry, Valls' ice-cream counter is temptingly open until around 11.00pm....