Begin by thoroughly rinsing the wild rice under cool tap water until the water is clear, then allow it to drain before adding it to your slow cooker.

In a food processor, pulse the onion, celery, carrots, and garlic until they're finely chopped, then place the mixture into the slow cooker.

Next, place 8 oz. of mushrooms in the food processor and pulse until they are finely chopped. Take the remaining mushrooms, slice them thinly, and add them to the slow cooker along with the processed mushrooms.

Blend the cannellini beans into a smooth puree and add this to the slow cooker, along with the bay leaf, garlic powder, and vegetable stock. Season the mixture with salt and pepper to taste, mixing well to ensure everything is evenly dispersed.

Cover the slow cooker and set it to cook on high for 3-4 hours or on low for 6-8 hours. Keep in mind that cooking times can vary between slow cookers, so it's advised to check the rice after 2½ hours (or 5½ hours on low). The cooked wild rice should be tender without becoming overcooked and mushy.

Upon completion of the cooking time, remove and discard the bay leaf. Gently stir in the tempered half and half and the chopped parsley. If necessary, add more vegetable stock until your desired consistency is reached.

Finally, adjust the seasoning with additional salt and pepper if needed, and serve the dish warm.