Cook the diced bacon in a large heavy-bottomed pot over medium heat until crispy. Remove with a slotted spoon and drain on paper towels, reserving 2 tablespoons of fat in the pot.
Add the onion, celery, and bell pepper to the pot. Sauté for 5 to 7 minutes until the vegetables are softened.
Stir in the minced garlic and cook for 1 minute until fragrant.
Sprinkle the flour over the vegetables and stir constantly for 2 minutes to create a roux and cook out the raw flour taste.
Slowly pour in the chicken broth while whisking continuously to prevent lumps from forming.
Add the potatoes, corn kernels, and dried thyme. Bring the mixture to a boil, then reduce heat to low and simmer for 15 to 20 minutes until the potatoes are tender.
Stir in the heavy cream and continue to simmer for 5 minutes until the chowder has thickened.
Season with salt and black pepper to taste.
Ladle into bowls and garnish with the reserved crispy bacon and chopped chives.