In a skillet over medium heat, add a splash of olive oil and brown the Italian sausage, breaking it apart with a spatula into small crumbles. Cook for about 5-7 minutes until the sausage is nicely browned and no longer pink. Once done, drain any excess grease and set the sausage aside to cool slightly.

In the same skillet, add the diced onion and sauté for 3-4 minutes until it's softened and translucent. Add the minced garlic and continue cooking for an additional 30 seconds until fragrant.

Transfer the browned sausage, sautéed onion, and garlic into the slow cooker. Add the diced potatoes, chicken broth, salt, pepper, and thyme, stirring to combine everything thoroughly.

Cover the crockpot with its lid and set it to cook on LOW for 6-7 hours or HIGH for 3-4 hours.

Once the cooking time is up, carefully stir in the heavy cream and cheddar cheese, if using, to create a rich and creamy texture.

Scoop generous ladles of the soup into bowls and garnish with fresh parsley or chopped green onions for a pop of color. Serve warm alongside crusty bread.