I'm happy to release Nashka's Lair, a mini-dungeon for a first-level party using the BECMI/RC rules written by Erin Bisson, who blogs as taichara at A Hamsterish Hoard of Dungeons and Dragons. While designed for BECMI/RC, this is easily adaptable to LL and/or B/X (man, that's a mouthful of acronyms!).
I've long been a quiet fan of taichara's monster creations and encounter ideas and magic items. I liked this first level mini-dungeon she posted back in 2009, as it was one of the first things I stumbled across when I returned to the first edition/classic edition RPG scene. I asked if I could compile this encounter as a PDF, and after many starts and stops on my end, here it is.