Time Out says
Built directly into the cliff face of Ebenalp, Berggasthaus Aescher-Wildkirchli is open May to November.
There's dinner with a view, and then there's the Aescher. This Swiss restaurant located high up in the Appenzeller mountains is both unique and stunning as it's built right into the cliff, with the rockface forming the building's fourth wall. Open from May to November, you can only get here via cable car, followed by a 15-minute walk across the Wildkirchli caves. Once you do arrive, you're in for a treat, because the restaurant serves some of the best rösti around, as you'd expect in the heart of the Appenzell. Add to this the amazing views of St Gallen and Lake Constance and you've got a pretty amazing destination all round.