Preheat the oven to 425°F. Line a large, rimmed baking sheet with nonstick foil or high-heat-resistant parchment paper and spray it with olive oil.

Wash the cauliflower heads, remove the outer leaves, and trim the very bottom of the core, keeping the core intact. Slice each cauliflower head into 3/4-inch-thick slices. The outer slices will fall apart. Simply roast them as florets with the steaks.

Use paper towels to dry the cauliflower slices and florets. Arrange them in a single layer on the baking sheet. Spray their tops with olive oil and sprinkle them with half the seasonings.

Bake the cauliflower slices for 15 minutes. Remove them from the oven, carefully flip them using two wide spatulas, spray them with more oil, and sprinkle them with the remaining spices.

Return the cauliflower to the oven and bake it until browned and fork-tender, 10-15 more minutes. Serve immediately.