Start by washing and peeling the russet potatoes. Slice them into even pieces to ensure uniform cooking. Next, chop the kielbasa into bite-sized rounds and dice the onion if you're using it. Gather all ingredients on your countertop to make the process efficient and seamless.

In your crockpot, layer the sliced potatoes first, followed by the chopped kielbasa and onion. Sprinkle garlic powder, salt, and pepper evenly over the layers.

In a separate bowl, combine your choice of milk or cream with the shredded cheese, mixing thoroughly until smooth.

Pour the cheese mixture over the layered ingredients in the crockpot, ensuring that the cheese sauce coats the potatoes and kielbasa evenly.

Cover the crockpot and set it to cook on low for 6-8 hours or on high for 3-4 hours.

During the last 30 minutes of cooking, stir in any remaining shredded cheese for extra melty goodness.

Once cooking is complete and the potatoes are tender, serve the dish warm. Consider garnishing with fresh herbs for a burst of flavor.