01 - Preheat oven to 425°F. Line a baking sheet with parchment paper.
02 - Remove the outer leaves and trim the stem of the cauliflower, keeping the core intact. Slice the cauliflower vertically into 4 thick steaks, about 3/4 inch thick each.
03 - Arrange the steaks on the prepared baking sheet. Brush both sides lightly with olive oil and season with salt and pepper.
04 - Roast in the preheated oven for 15 minutes. Flip the steaks carefully and roast for 10 more minutes, until just tender and golden.
05 - While the cauliflower cooks, combine mozzarella, parmesan, cream cheese, milk, Dijon mustard, garlic powder, smoked paprika, and a pinch of salt and pepper in a medium bowl. Mix until smooth.
06 - Remove cauliflower from oven. Spoon the cheese sauce evenly over each steak. Sprinkle with breadcrumbs if desired.
07 - Return to oven and bake 5 to 7 minutes, or until cheese is melted, bubbling, and golden brown.
08 - Garnish with fresh parsley. Serve hot.