Add the uncooked wild rice, chicken breasts, mirepoix, garlic, chicken broth, poultry seasoning, garlic powder, onion powder, and chicken base to a slow cooker.

Cover and cook on low for 6 hours.

If possible, remove the chicken after 3 hours to help prevent overcooking. Cut or shred the chicken and refrigerate until needed. Otherwise, shred the chicken directly in the slow cooker after the full cooking time.

Check that the wild rice grains have opened and that only a small amount of liquid remains before finishing the soup.

Warm the milk in the microwave for 60-90 seconds to help create a smoother bechamel.

Melt the butter in a saucepan. Stir in the flour and cook for 1 minute.

Add 1/2 cup of milk at a time, whisking between additions, until all the milk is incorporated and the mixture has thickened into a creamy base.

Season the thickened mixture with salt.

Add the bechamel, chicken, and heavy cream to the slow cooker and stir until evenly combined.

Adjust the consistency with additional broth or milk as desired. Season with extra salt and pepper, or add a dash of sherry if preferred.

Serve the soup with bread for dunking.