Add the leeks, garlic, cauliflower, potatoes, broth, coconut milk, nutritional yeast, thyme, and salt to the slow cooker. Cook on high for 4 hours or low for 8 hours.
Open the slow cooker and remove the thyme sprigs. Use an immersion blender to blend the soup until smooth or your desired consistency. Alternatively, you can transfer the contents to a high speed blender.
Add the cream cheese and 1 cup of plain milk and stir until melted and combined. Add black pepper and additional salt to taste. Serve immediately, and top with chopped chives, thyme, and bacon bits, if desired. Enjoy!
Notes
Storage Instructions: Leftover potato leek soup will keep in an airtight storage container in the refrigerator for up to 5 days. Before storing, allow the soup to cool to room temperature.
Freezing instructions: This soup can be frozen after cooking and will keep for up to 3 months. I like to freeze it in 1-cup or 2-cup portions using my Souper Cubes. Then defrost from frozen on the stovetop over low heat until thawed and creamy again.