Cook the chicken in a large pot or Dutch oven over medium heat until browned, about 5-7 minutes.

Add the diced onion to the pot and cook until softened, about 3-4 minutes.

Add the minced garlic and cook for an additional minute.

Add the diced potato, frozen corn kernels, and cooked chicken back to the pot and stir to combine.

Sprinkle the flour over the top of the potato and chicken mixture, stirring to combine, and cook for 1-2 minutes.

Gradually add the chicken broth and milk to the pot, whisking constantly to avoid lumps, and bring the mixture to a boil.

Reduce the heat to low and simmer for 10-15 minutes, or until the potatoes are tender.

Stir in the shredded cheddar and Monterey Jack cheese until melted and smooth.

Season the chowder with salt, pepper, and dried thyme.

Serve the cheesy chicken chowder hot, garnished with chopped herbs or crusty bread if desired.