Reddit mentions of Smoki Peanut Flavored Snacks 150g

In Serbia it's not customary to exchange gifts for Xmas, also if she is Orthodox, the Xmas is on January 7th.

Smoki is a type of snack with peanut butter that's quite popular.

http://www.amazon.com/Smoki-Peanut-Flavored-Snacks-150g/dp/B000LRFW4G

Plazma (they are sold as Lane Biscuits in the west)

http://www.amazon.com/Bambi-Plazma-Lane-Biscuits-600g/dp/B000LRKLEW/

Jaffa Cakes (most popular ones are from Crvenka, but Milka makes them too)

http://www.amazon.com/Jaffa-Cakes-Biscuit-Covered-Chocolate/dp/B000LRIG6W/

Munchmallow Classic (because of poor packaging these have a habit of not being fresh when you buy them)

http://www.amazon.com/Crvenka-Jaffa-Munchmallow-Classic-105g/dp/B000LRKLGK/

Eurocrem (a nutella like spread)

http://www.amazon.com/Eurocrem-Hazelnut-Milk-Cocoa-Spread/dp/B000LQNBLS/

Eurocrem bar (the same thing just in a shape of a bar)

http://www.amazon.com/Eurocrem-Hazelnut-Milk-Cocoa-100g/dp/B000LQLN4U/

Čokoladne bananice

http://www.amazon.com/Stark-Chocolate-Covered-Flavored-Dessert/dp/B000LQJK04/

Bajadera (Croatian but popular in Serbia)

http://www.amazon.com/Kras-Bajadera-Nougat-Dessert-500g/dp/B000LQNB72/

Except you said she doesn't like liquorice? One of the main ingredients of Negro bonbons is lakric (syrup of the sladić plant/liquorice plant). I had to google these things to make sure, so that's why the links, if somebody knows better. edit:yup it's liquorice just click on the ENG in the upper-right corner on the first link in my comment.

Then again I've never had actual "liquorice" so I don't know how similar in taste it is to Negro bonbons and whether she'd (does) like them. Negro is only part liquorice, it's also mint and honey and stuff.

Looking around there maybe get her one of these other things (personally I like the "Hazelnut toffee")? Or kidy chocobars.

Speaking of the more popular domestic stuff personally I'd recommend medeno srce (honey hearts), they're like little heart-shaped cake-cookies. Or Plazma, or Smoki (check my name), Jaffa Cakes, Eurocrem, Eurocrem bar, Čokoladne bananice, Domacica, or anything from Stark or Pionir.

Not Serbian but popular stuff are stuff like Milka, or the usual Mars, Twix whatnot.

Damn, I'm hungry now.

https://www.amazon.com/Smoki-Peanut-Flavored-Snacks-150g/dp/B000LRFW4G