In a skillet over medium heat, cook the chopped bacon until crispy. Remove the bacon and set aside, leaving the drippings in the skillet.
Add the diced onion to the skillet and sauté until translucent, about 5 minutes. Add the minced garlic and cook for an additional minute.
Transfer the cooked bacon, sautéed onion, and garlic to the slow cooker. Add the diced potatoes, chicken broth, corn, thyme, salt, black pepper, and cayenne pepper (if using).
Stir to combine all ingredients, then cover and cook on low for 6-8 hours or on high for 3-4 hours, until the potatoes are tender.
About 30 minutes before serving, stir in the heavy cream. If the chowder is too thick, add a little more chicken broth to reach your desired consistency.
Once ready, taste and adjust seasoning if necessary. Serve hot, garnished with fresh parsley.