5 slices bacon
1 small onion chopped
2 tbsp all-purpose flour
1 1/4 cups milk
1 1/4 cups chicken broth
1 1/4 cups shredded Monterey jack cheese
Salt and pepper
4 thick slices white bread toaste
1 tomato sliced
3 cups shredded or sliced roast turkey
Preheat the broiler. Cook the bacon in a large skillet over medium heat until crisp, about 10 minutes. Transfer to a paper towel-lined plate. Pour out all but about 1 tablespoon fat from the skillet.
Make the gravy: Add the onion to the skillet and cook, stirring until soft, about 3 minutes. Add the flour and cook, stirring 1 more minute. Increase the heat to medium high, add the milk and chicken broth and bring to a boil, stirring. Reduce the heat to medium low and simmer, stirring until slightly thickened, about 6 minutes. Remove from the heat and stir in 1 cup of cheese. Season with salt and pepper to taste.
Arrange the bread on a baking sheet. Spread each slice with mustard, then drizzle with some of the gravy and top with the sliced tomato. Toss the turkey with the remaining gravy in the skillet. Divide the turkey evenly among the bread slices, then sprinkle with the remaining 1/4 cup of cheese. Broil until golden, about 2 minutes.
Crumble the bacon over the sandwiches before serving.