Wash and peel the potatoes, then dice them into roughly 1-inch cubes. Chop the onion and mince the garlic. Gather all ingredients before starting.
Place the diced potatoes and chopped onions into the slow cooker. Add the minced garlic on top and season with a little salt and pepper.
Pour the chicken broth over the vegetables, ensuring they are mostly submerged. Cover with the lid and set the slow cooker to low.
Let the mixture cook on low for 6 to 8 hours, until the potatoes are very tender and starting to break down, filling your kitchen with a warm, savory aroma.
About 30 minutes before serving, use an immersion blender directly in the slow cooker or a potato masher to mash or blend the potatoes until the soup is smooth, creamy, and velvety.
Stir in the milk or cream along with the shredded cheddar cheese. Continue stirring until the cheese melts completely, creating a rich, cheesy texture. Taste and adjust seasoning as needed.
If desired, cook bacon until crispy, then crumble and sprinkle on top of each bowl for added smoky flavor and crunch.
Let the soup rest for 5 minutes off heat so flavors meld and it thickens slightly. Ladle into bowls, garnish with bacon or herbs if you like, and enjoy the warm, velvety goodness.