NOTE: If using homemade chicken stock and homemade salsa you will probably not need to add more seasonings, because there is so much flavor and vegetables already in both. If using store bought broth and salsa you may want to saute some onion and garlic and add to the broth and add more granulated garlic, onion, pepper and salt.
Reheat broth on stove top. Remove 2 c of broth for cheese sauce and set aside. Add salsa and chicken to pot of broth and continue to heat.
Meanwhile make a roux with the 1/2 c butter and 1/2 c of flour. Add 2 c of hot stock to roux, make sure you remove all lumps. Add room temp canned milk. Once roux is thickened remove from heat and add cheese. If cheese becomes stringy, add a couple dashes of lime juice. Stir until melted.
Add cheese sauce back into pot of soup, stir to combine. Add granulated garlic and onion, black pepper and thyme. Simmer for about 10 min, taste and add salt and re-season if needed.
Boil pasta to al dente, drain and add to soup pot.
Serve with sour cream, cilantro, or any of your favorite Mexican flavored condiments. Cotjia cheese would be a great addition.