Preheat the oven to 200°C or 400°F (fan-forced).

Rinse the cauliflower and chop it into bite-sized florets. Toss with 2 tablespoons of olive oil, salt, and pepper until evenly coated. Spread on a baking tray and roast for about 20 minutes until tender and slightly golden.

While the cauliflower is roasting, make the cheese sauce. In a saucepan, melt the dairy-free butter over medium heat. Stir in the plain flour and cook for 1-2 minutes until it forms a smooth paste. Gradually whisk in the dairy-free milk until smooth and thickened. Add the nutritional yeast, salt, and garlic powder, stirring constantly for another minute or so until the sauce is creamy. Remove from heat. Taste and adjust the seasoning if needed.

Transfer the roasted cauliflower into the saucepan with the cheese sauce and mix to combine, making sure all the cauliflower is coated into the sauce. Transfer the cheesy cauliflower into a small casserole dish (see notes on size).

In a small bowl, mix together the panko breadcrumbs, nutritional yeast, chopped fresh parsley, salt, garlic powder, and olive oil until well combined. Sprinkle the breadcrumb mixture evenly over the cauliflower.

Return the dish to the oven and bake for an additional 20 minutes or until the breadcrumbs are golden brown and the sauce is bubbly. Once baked, remove from the oven and allow to cool slightly before serving.