Slowly pour in the milk, whisking with a nylon whisk until evenly incorporated and starting to thicken.
Add chunks of the brie and nutmeg and continue stirring until the brie is melted.
Carefully nestle in the cauliflower florets and stir to coat.
Season with salt and pepper, transfer the entire pan into the oven and bake for 30-40 minutes. After 20 minutes, top with the breadcrumbs and parmesan cheese, place back into the oven and continue baking until bubbly and the cauliflower is tender. Serve immediately.