In a large stockpot, combine the broth, potato, corn, garlic, marjoram, thyme, and pepper. Bring to a boil. Reduce the heat; cover and simmer until the potatoes are tender, about 15-20 minutes.
In a separate bowl, whisk the flour and milk until smooth. Gradually add to the vegetable and broth mixture.
Bring the chowder base to a boil, and stir until slightly thickened, about 2 minutes. Reduce the heat and stir in the cheese until melted.
Add the cooked, cubed chicken and continue to stir until everything is heated through. Remove from the heat and serve immediately.
Notes
*Note, to speed up the recipe you can use 2 cups of cooked and shredded rotisserie chicken in place of the baked chicken breasts. Optional: I like to garnish mine with some fresh chives or chopped green onions. You could also add a dollop of sour cream or sprinkle on some more cheese.