There's a ton of burger joints in Copenhagen, but this fastfood chain makes gourmet burgers at a reasonable price. The menu is simple, but better quality than several of the more well-established burger cafés.
Prices are between 12-18€ for a menu, and there's a vegetarian version as well. While it's not exactly cheap, it's a decent price for high quality in an expensive city like Copenhagen. It's located both in the city center, in Nørrebro and Østebro
I'd recommend the bacon and avocado menu!