Heat a Dutch oven or other large heavy pot over medium heat. Add the chopped bacon and cook until browned, about 6-8 minutes.
Use a slotted spoon to transfer the cooked bacon to a paper towel lined plate, leaving the bacon grease in the pot. Let the cooked bacon cool and then refrigerate it while the soup cooks.
Add the onion, celery and carrot to the bacon grease in the pot. Cook over medium heat, stirring occasionally, for about 6 minutes, until softened.
Add the garlic, potatoes, thyme, salt and pepper. Cook, stirring often, for 2 minutes.
Stir in the split peas and vegetable broth.
Bring soup to a boil and then reduce the heat to a simmer. Cover the pot and simmer the soup, stirring occasionally, for 75-90 minutes, or until peas are tender and have broken down and soup has thickened. If the soup is not thickening as much as you'd like, you can uncover it during the last 20 minutes of the cook time.
Taste the soup and add additional salt and/or pepper if needed. (Remember that the bacon will add saltiness if you will be serving the soup with bacon on top.)
Serve soup garnished with the chopped cooked bacon.