Preheat the oven or a toaster oven to 400 degrees F (200 degrees C). Spread the Brie cheese onto two slices of bread, and top with remaining slices. Place on a baking sheet and toast in the oven for about 8 minutes, turning once halfway through. Cut in half, and set aside.
In a saucepan over medium heat, stir together the tomato puree, red pepper flakes, black pepper, basil, and sugar. Bring to a simmer, and cook for 10 minutes.
Whisk in the cream cheese until well blended, then stir in the milk. Heat through without bringing to a boil. Stir in the fresh basil, and remove from the heat.
To serve, place each sandwich half into a separate bowl. Ladle soup over each one into the bowl. Serve immediately.
