Preheat the oven to 425F convection or 450F regular bake. Line a baking sheet with parchment paper.
Add the cauliflower to the baking sheet. Drizzle with the olive oil and sprinkle with the salt and pepper. Use your hands to toss to coat and massage the oil into the cauliflower. Spread out into an even layer and bake for 20-25 minutes or until the cauliflower is charred.
Meanwhile, add the pecans to a blender and pulse until finely chopped. Add the parmesan and pulse again to combine.
Remove the cauliflower from the oven and sprinkle the pecan/parm mixture all over. Bake for 8-10 more minutes or until the cheese and nuts are golden (be careful not to burn) . Allow to cool off for at least 10 minutes.
Meanwhile, in a large bowl, add the lemon, onion, and salt and mix together. Let sit for at least 10 minutes or overnight. Then whisk in the oil and parmesan until combined (it will be chunky).
Transfer the cauliflower to the large bowl along with the parsley and toss to coat thoroughly in the dressing. Transfer to a serving platter or large plate and top with pecans and cranberries.