Preheat oven to 400 degrees. Coat shallow baking sheet with cooking spray.
Place cauliflower core side down on a cutting board. Slice into 1-inch thick steaks, the ends will fall apart into florets. You should be able to get 4 1-inch thick steaks.
Coat baking sheet with olive oil. Place steaks on prepared baking sheet and drizzle with olive oil.
Bake 15 minutes on one side. Turn over and cook another 10 - 15 minutes until nicely browned.
Meanwhile, combine melted butter and hot sauce in a saucepan. Brush cauliflower liberally and bake an additional 3 minutes. Turn over cauliflower and baste again with remaining hot sauce; bake 3 minutes.
To make grilled cheese...
Butter bread slices and pan grill, topped with Havarti cheese, roasted buffalo cauliflower steaks, blue cheese crumbles, more Havarti. Turn until golden brown on both sides.