Preheat the oven to 450 degrees F (230 degrees C).

Remove all green leaves and stems from the core of the cauliflowers. Trim core but do not remove the core as it helps hold the cauliflower steaks together. Cut cauliflower lengthwise into 1/2 inch thick slices.

Rub both sides of cauliflower slices with olive oil and steak rub. Set cauliflower slices onto a baking sheet.

Roast in the preheated oven for 30 minutes. Flip cauliflower steaks and roast until lightly browned and cooked through, 15 more minutes. Sprinkle with chopped parsley before serving.