Ljubljana has many dining options from traditional Slovenian food to contemporary dishes based on these traditional ones. There are beautiful traditional cafes to small cafes along the river. I recommend the following:
Kavarna Union: This is an old-world café that is on the first floor of the Hotel Union. It is a perfect spot for a coffee and tea after a full-day of exploring. I enjoyed a latte and their famous Union Slice cake or Union Rezina with chocolate and vanilla cream. Miklosiceva 1.
Gostilna Na Gradu: This restaurant is considered one of the best in town and is located in the Castle above the city. I enjoyed my lunch with an entrée of sea bass with broccoli, and cauliflower in a broccoli cream. They do have a tasting menu as well featuring seasonal, local produce. They have a more traditional dining room with brick walls and a ribbed ceiling and a lovely glass room overlooking the plaza of the Castle. This is a great, bright spot for lunch.
Gujzina: Featuring Slovenian cuisine from the Perkmurje region near Hungary, I wanted to try this spot near my hotel. It had a casual, contemporary design and a very reasonably priced menu. I enjoyed trying a locally brewed ale that was done just for the restaurant. I also enjoyed a lovely salad with a pumpkin oil and balsamic dressing and a very nice pork tenderloin with potato dumplings in a plum and plum brandy sauce. The service was really good as well. Mestni Trg 19.
The Vander Restaurant at the Vander Urbani Resort serves the breakfast buffet as well as lunch and dinner. Their chef is Benjamin Launay from France. Having just arrived I enjoyed dinner in the restaurant with a stuffed salmon dumpling and a nice glass of Slovenian red wine, a Movia cabernet. Krojaska Ulica 6-8.
Vinoteka Movia has a wine bar in town where you can try more of their local wines.
Lolita: This is a wonderful spot for coffee, pastries and cakes across from the Three Bridges in the heart of the Old City. I loved trying the traditional Slovenian apple cake with walnuts, poppy seeds, cottage cheese. It has a great contemporary decor with beautiful painted ceilings. Cankarjevo Nabrezje 1.
Slascicarna pri Vodnjaku: This is a charming small sweet and ice cream shop at Stari trg 30. It is charming inside and they do have nice outdoor café seating.
Julija: Friends who spent a lot of time in town, love this spot for Slovenian specialties with a Italian or Mediterranean twist.
I read about and saw Restavracija Strelec in the Archers Tower of the Castle. It comes well-recommended, with the chef from Noma in Copenhagen. Spajza Restaurant also gets good reviews for local dishes.