01 - Preheat the oven to 425°F. Line a large baking sheet with parchment paper.
02 - Remove the green leaves from the cauliflower heads and trim the stem, keeping the core intact.
03 - Slice each cauliflower head into 1-inch-thick steaks (you should get 2–3 steaks per head; reserve any loose florets for another use).
04 - Arrange the cauliflower steaks in a single layer on the prepared baking sheet.
05 - In a small bowl, mix together the olive oil and all spices until well combined.
06 - Brush both sides of each cauliflower steak generously with the spice mixture.
07 - Roast in the preheated oven for 25–30 minutes, flipping halfway through, until golden brown and tender.
08 - Transfer to serving plates. Garnish with chopped parsley and nuts, and serve with lemon wedges if desired.