I made these lingonberry bars a couple months ago. They are great - buttery with a little chew and not too sweet. I used lingonberry jam that I purchased at Ikea, but raspberries or anothet tart jam or fruit would work really well. Even a cranberry compote would work (or how about cranberry and marmalade? now I want to make that....)
I got the recipe from this great blog "17 and Baking". She's pretty impressive! I definitely wasn't such an ambitious baker at her age (she's in college now).
I added some coconut and walnuts to these but otherwise stuck pretty close to the recipe: