How to Make It
In a small saucepan, bring the milk to a simmer. In a medium saucepan, melt the butter. Add the flour and whisk over moderate heat for 1 minute. Gradually whisk in the hot milk and bring to a boil. Cook, whisking, until thickened, about 5 minutes. Remove the pan from the heat and whisk in both cheeses until melted. Stir in the nutmeg and hot sauce and season with salt and pepper.
Preheat the oven to 425°. Arrange the bacon on a rack set over a baking sheet. Cook until golden and crisp, about 30 minutes.
Preheat the broiler. Arrange the tomato slices on a baking sheet, drizzle with the oil and season with salt and pepper. Broil 6 inches from the heat until lightly charred, 1 to 2 minutes per side; keep warm.
Arrange the bread on a foil-lined baking sheet and spread each slice with 1/2 tablespoon of the butter; season with salt and pepper. Broil until lightly toasted, about 2 minutes. Flip the bread and toast for 1 minute. Top each toast with some turkey and a slice of tomato. Spoon the sauce on top and sprinkle on both cheeses. Broil until the cheese is melted and golden brown, 2 to 3 minutes. Transfer the sandwiches to plates and top with the bacon. Garnish with chopped chives and parsley and serve hot.