There are 2 restaurants that we would highly recommend.
Il Giardino at the bottom of the square - yes, it's Italian, but the food is fantastic. It's not often that we eat at the same place twice during a holiday, but when we were in Pollensa for 1 week in October 2007, we ate at Il Giardino early in the week and enjoyed it so much that we went back on the last evening, and enjoyed it just as much as the first time. We're certainly planning a meal there this year.
The second one, unfortunately I don't know the name of (!) but if you stand in the square with Il Giardino behind you and look at the church in front of you, there is a small alleyway/path to the right of the church, that goes up between the side of the church on the left and a small bar on the right. Follow that alleyway, and it does a swift right and then left - at the point where it turns left is a tiny little restaurant that doesn't look like anything - in the evening they have about 2 or maybe 3 table outside in the alleyway. It's a fantastic place to sit and people watch, but the suckling pig is to die for. In fact, it's so good that when we are over next month, it is our daughters 21st birthday, and she has already declared that we are going to this particular restaurant for her birthday meal!! Suits me fine!!!!