01 - Set the oven to 425°F and line a large baking sheet with parchment paper.
02 - Remove leaves and trim bases of cauliflower heads, keeping cores intact. Slice each head into 1-inch thick steaks, reserving loose florets for another use.
03 - Place cauliflower steaks evenly on the prepared baking sheet.
04 - Whisk olive oil, cumin, smoked paprika, garlic powder, salt, and black pepper in a bowl. Brush mixture onto both sides of the cauliflower steaks.
05 - Bake for 20 minutes, flipping halfway, until steaks turn golden and tender.
06 - Combine harissa paste, lemon juice, and maple syrup or honey in a small bowl, stirring until smooth.
07 - Remove cauliflower from oven, brush generously with harissa glaze, then return for an additional 5 to 7 minutes until caramelized.
08 - Transfer steaks to plates, garnish with chopped parsley, and serve immediately.