Use a mini loaf pan or a small rectangular glass container. Line it with a 'sling' of parchment paper so the edges hang over the sides for easy lifting later.
Use a mandoline to slice the potato and the peeled broccoli stem core into 1–2 mm rounds.
Bottom: 2 layers of potato (brush each with herb butter, lemon zest, and a tiny pinch of parmesan).
Middle: 6 layers alternating broccoli and potato (apply butter/cheese every second layer).
Top: 2 layers of potato (brush with butter).
Cover tightly with foil. Bake at 180°C for 30–35 minutes. Check with a toothpick; it should feel like soft butter.
Refrigerate for 4 hours
Final heating at 200°C for 10 - 15 minutes