Preheat oven to 385 degrees.
Prep the cauliflower by using a sharp knife to remove outer leaves and outer core.
Rub the cauliflower with olive or avocado oil and cover with aluminum foil.
Bake in a cast iron skillet or baking dish for 30 minutes.
In a bowl, combine: mayo, dijon, salt, pepper, lemon juice & zest, parmesan cheese, paprika and chili powder.
Remove cauliflower from oven and uncover. Using a spoon, spread the mixture all over until the outside of the cauliflower is coated. Depending on the size of the cauliflower, there may be extra sauce.
Bake the cauliflower, uncovered, for another 30 minutes.
Slice like a cake and serve with lemon wedges.