Look at Osteria Poggio in Center Harbor.
https://www.osteriapoggio.com/
It is one of our favorites. For our 49th Anniversary I reserved the cupola at the top of the roof. Room for one table and two chairs. Multiple windows. You can order off the menu or talk to Sweets the owner/chef and do a customized chef’s menu which can be different items for each of you. But note that it requires you to go up 4 flights of stairs, some of which are not as long as the others. It was a home run and we did the chef’s menu (I met in person with Sweets to plan the menu)