Steam whole head of cauliflower for five minutes, (If using instant pot, steam for two minutes and quick release).While cauliflower is steaming, mix together mayo and Parmesan cheese. Set aside.
Remove cauliflower from steaming pot and place on parchment paper lined baking sheet. Slather the mayo and cheese mixture all over the top of the steamed cauliflower head.
During the last few minutes of baking your cauliflower turn the oven to broil for 1-3 minutes, or until the top of your cauliflower is browned and slightly crisped.Remove the cauliflower from the oven and place on counter top to cool slightly. Slice into six wedges. Serve and enjoy.