Bring a large pot of water to boil. Add the cauliflower florets and let them cook five minutes. Drain immediately and pat the florets dry, or spread them on a baking sheet and let them air-dry for a few minutes.
Blend the cashews with garlic powder, onion powder, nutritional yeast, salt, ground black pepper and vegetable stock or water. Set aside.
Preheat the oven to 400 degrees Fahrenheit.
Heat 1 tablespoon olive oil in a skillet. Add the tapioca starch and stir until it darkens a bit. This is your roux which will help thicken the sauce.
Stir in the blended cashew cream. Stir quickly as you add the cream because the tapioca will cause it to lump up. If lumps do form, just break them with the ladle.
When the cashew cream boils add the thyme or oregano and nutmeg. Let the cream reduce and thicken, about five minutes. Check seasoning and add more salt and pepper if needed.
Coat a baking dish with cooking spray or oil. Place the cauliflower florets in the dish evenly. Then pour the white sauce all over it.
Place the baking dish in the oven and let it bake 20 minutes.
Meanwhile, make the optional breadcrumb topping, if using, by mixing the breadcrumbs, vegan parm, oil and ground pepper and salt.
After the cauliflower has baked 20 minutes, remove it from the oven and sprinkle the breadcrumb topping over it. Return to the oven and bake 10 more minutes or until the topping is golden and crunchy.If you aren't using the topping, just let the cauliflower bake 10 more minutes. Remove from the oven and let stand 10 minutes. If using parsley, sprinkle it on before serving.