My personal favorite of his is the Schattengang demo, definitely worth a look if you like gloomy death metal ala Asphyx and early Crypt of Kerberos. He elongates minimalist doom/death aesthetics into long-winded Burzum-style textural explorations, and then enriches it all with some really well-done synthesizer work reminiscent of classic krautrock at points.
I would probably start with the trilogy of Winterkälte, Kristall und Isa, and the self-titled first, though. Those albums are the most representative of what Paysage d'Hiver his, compared to outliers like Schattengang and Die Festung (where the '70s German synth influences are most obvious). The first song on the self-titled in particular is excellent, melding the elegant melodicism of an At the Gates or a Sacramentum with the epic drone of Filosofem. It's even got some The Red in the Sky Is Ours-style violin accompaniment!
I got into Paysage d'Hiver in kind of a weird round-a-bout way. I downloaded Nacht and put it on as background music while reading a Cormac McCarthy novel (either Outer Dark or Child of God, can't remember which) in one marathon session, and the music took about two years to fully infect my brain (I had a very similar experience with Branikald).
I see Darkspace as something of a continuation of this project, but personally I prefer Paysage d'Hiver. The Ruins of Beverast offers a similarly heady Germanic take on atmospheric black metal.