Stir in garlic and cook for another 1 minute until fragrant.
Add the diced potatoes and chicken broth. Bring to a boil, then reduce heat and simmer for 10-12 minutes or until potatoes are tender.
Stir in the corn, cooked chicken, thyme, salt, and pepper. Simmer for 5 more minutes.
In a small bowl, mix the flour with milk until smooth (if using for thickening), then stir into the pot. Cook for another 3-4 minutes, stirring frequently.
Add the heavy cream and simmer gently for 3-4 minutes, avoiding a full boil.
Adjust seasoning if needed and serve hot, garnished with fresh parsley if desired.
Notes
For a lighter version, use half-and-half instead of heavy cream.
Rotisserie chicken works well for quick prep.
Smoked paprika or bacon bits can add a smoky depth to the chowder.