Preheat the oven to 350 degrees F. Melt the butter in a pot over medium-high heat. Add the onion, celery and garlic and cook, stirring, until softened, about 4 minutes. Stir in the flour and cook, stirring, 1 minute. Add the broth and cream; bring to a boil. Reduce the heat to medium low, then stir in the American cheese and 1 cup cheddar until melted. Add the ham and turkey and heat through, 3 to 4 minutes. Remove from the heat and keep warm.
Spread the baguette slices on a baking sheet and brush with melted butter. Transfer to the oven and toast until golden, about 10 minutes. Meanwhile, cook the bacon in a nonstick skillet over medium heat, turning, until crisp, about 10 minutes; drain on paper towels, then crumble.
Toss the tomatoes, parsley, and salt and pepper to taste in a bowl. Ladle the soup into bowls and top with the toasted baguette, the remaining 1/2 cup cheddar, the tomato-parsley mixture and bacon.