Peel the potatoes and cut roughly. (Note: if using a sweet potato, dice it into ¼" cubes.)
Dice the onion, pepper, and carrots.
Cut chicken into bite-sized pieces and sear in a large pot with butter or olive oil over medium-high heat until browned. You are only looking to lightly sear the meat; it will finish cooking in the chowder.
Add all of the vegetables (including potatoes), as well as the broth and garlic powder to the pot. Cover and reduce heat to low for 90 minutes, stirring occasionally.
After 90 minutes, the potatoes should be easily pierced with a fork. If not, resume cooking until the potatoes are ready. (Note: if you are using a sweet potato, don't worry about whether it's softened.)
Combine milk and corn starch, and stir.
Add the milk mixture to the pot and stir. Cover and raise heat to medium-high until the chowder begins to thicken, approximately 5 minutes, stirring occasionally.
In the meantime, slice the mozzarella and cube the bacon / pancetta.
Once the chowder is thickened, use a potato masher or large fork to mash the softened potatoes. This will make the chowder a bit more creamy.
Add salt and pepper (and red pepper flakes if you'd like) to taste. Note that you will probably need a generous amount to properly adjust the seasoning but don't overdo it; people can always add additional seasoning as the dish is served.
Turn heat down to low and stir in the fresh mozzarella. Continue stirring until the mozzarella is fully melted into the chowder. Cover the chowder to keep it warm.
Fry the cubed bacon or pancetta in a small skillet over medium heat until crispy. Remove with a slotted spoon to a plate covered with a paper towel to drain.
Ladle the chowder into bowls and sprinkle bacon / pancetta bits for color. Eat with a chunk of rustic bread.