I recommend Viking Bakery in Denvile. It's been in business for ever, and still uses the old time family recipes. They are kosher, so they use real butter in the pastries, to. They do rotate goodies as they make so many varieties of items, more than the displays can, so calling ahead to see if they made apple strudel that day is a good idea. (or even to order it for the date you have in mind) http://www.viking-bakery.com/index.htm
The other place I recommend in not located up north, but rather in Flemington. The Dutch Farmers Market has a bakery inside and they make all sorts of really good baked items, just like grandma's. I really enjoyed their apple strudel. Though I believe they too rotate what items they carry each week. The market is open Thur - Sat, and the bakery's phone number is (908) 806-3904.