Heat a large stockpot or Dutch oven over medium high heat. Add bacon and cook until brown and crispy, about 6-8 minutes; drain excess fat, reserving 1 tablespoon. Stir in chicken and cook until golden, about 2-3 minutes.
Add garlic and onion, and cook, stirring often, until onions have become translucent, about 3-4 minutes. Stir in chicken broth, tomatoes, milk, red pepper flakes, pasta, salt and pepper, to taste. Bring to a boil; cover, reduce heat and simmer until pasta is cooked through, about 13-16 minutes.
Stir in barbecue sauce and cheese until heated through, about 1-2 minutes.