In a medium saute pan over medium-high heat, cook the bacon until the fat has rendered and the bacon is crispy, 7 to 8 minutes. Using a slotted spoon, remove the bacon from the pan and place on a paper towel-lined plate. Reduce heat to medium, then add the flour to the fat in the pan and whisk until smooth. Cook, stirring often, until nutty and fragrant, 3 to 4 minutes. Pour in the milk in a slow steady stream while whisking constantly. Whisk until smooth. Bring to a boil, then reduce heat and simmer 7 to 8 minutes. Stir in the Brie, 1 teaspoon of the salt and the nutmeg, stirring until the Brie is melted. Add 3/4 of the bacon and stir to combine. Remove from the heat and keep warm while you prepare the cauliflower.
Preheat a grill to medium high and wipe down the grates with a towel dipped in canola oil to clean and create a nonstick surface. Drizzle the cauliflower florets with olive oil and season with the remaining 1 teaspoon salt and the pepper. Grill cauliflower until it is caramelized and charred on all sides, 7 to 8 minutes. Remove from the grill and place on a large platter. While still hot, spoon the bacon and Brie mixture over the top. Garnish with the remaining crispy bacon and parsley.