Beat cake mix, cold water and eggs in large bowl with mixer until blended. Add peanut butter; mix well. Pour into 4-qt. slow cooker sprayed with cooking spray.
Break 2 oz. chocolate into small pieces; place in same bowl used to prepare cake batter. Add boiling water; let stand 1 min. Stir until chocolate is completely melted. Pour over batter in slow cooker; cover with lid.
Cook on LOW 2-1/2 to 2-3/4 hours (or HIGH 1-1/2 to 1-3/4 hours) or until toothpick inserted near center comes out with fudgy crumbs. Turn slow cooker off.
Microwave remaining chocolate and COOL WHIP in microwaveable bowl on HIGH 1 to 1-1/2 min. or until chocolate is completely melted and mixture is well blended, stirring with whisk after 45 sec. Spread over cake; sprinkle with nuts. Serve warm.
Serve with frozen vanilla yogurt.
Prepare using a yellow or spice cake mix.
Calories From Fat
% Daily Value*
Total Fat 18g
Saturated Fat 6g
Trans Fat 0g
Total Carbohydrates 21g
Dietary Fiber 3g
* Percent Daily Values are based on a 2,000 calorie diet.
* Nutrition information is estimated based on the ingredients and cooking instructions as described in each recipe and is intended to be used for informational purposes only. Please note that nutrition details may vary based on methods of preparation, origin and freshness of ingredients used.