Preheat the oven to 350 degrees F. (You can go upwards of 500 degrees F if you want to expedite the steaks as cooking only takes 25 minutes then instead of an hour, but 350 degrees F is best if you are cooking other veggies in the oven!)
Cut off stems and leaves of both heads of cauliflower and then rinse with water + pat dry. Make sure you don't cut too much of the stem/core off the cauliflower or the "steaks" will fall apart!
Slice each cauliflower in half down the middle and then cut 1 to 1.5 inch "steaks". You will get about 4 steaks give or take. Don't worry if small florets fall off as you can still throw them on the baking tray anyways.
In a small bowl, add olive oil + spices and whisk together. Then using a basting brush, brush the marinade on both sides of the cauliflower steak (+ any separate florets) and place on a baking pan. If you don't have a basting brush, you can just drizzle it on.
Cover the baking pan tightly with foil, and place in the oven on the bottom rack. Bake with the foil on for about 15 minutes to steam the cauliflower.
Take off the foil and continue to bake for another 45 minutes. You will need to carefully flip the cauliflower steaks halfway through to make sure each side gets nice and brown. Option to broil for the last few minutes if you like your steak extra crispy!