Melt the butter in a large pot over medium heat.
Add the garlic and chopped onion.
Sauté until softened, about 5 minutes.
Add the flour to the pot.
Stir well and cook for 1 minute more.
Pour in the chicken broth and half-and-half.
Stir constantly to combine.
Mix in the cream of chicken soup and salsa.
Continue to stir until everything is well combined.
Add the shredded chicken, black beans, corn, cumin, and fajita seasoning.
Simmer over low heat for about 15 minutes.