Place a small baking dish inside your crockpot to be sure that it will fit, then spray the inside well with cooking spray.
Mix together all ingredients and pour into the small baking dish.
With additional water, fill the crockpot on the outside of the baking dish until the water reaches halfway up the outside of the inner dish. Cover and cook on low for 8 hours.
Top with butter if desired, as well as yogurt, peach slices, and walnuts. Serve immediately.