For Pancakes: HEAT large skillet or griddle to medium high. Combine cake mix pouch, water, oil and eggs in large bowl. Melt butter on griddle. Pour 1/4 cup cake batter onto skillet. Cook 3 minutes. Turn; cook 2 to 3 minutes.
For Sauce: MICROWAVE water, filling mix pouch, caramel topping, peanut butter and butter in medium microwave-safe bowl on HIGH 30 seconds; stir. Repeat 2 times until sauce is warm and smooth. Whisk in additional water if needed for creamy consistency.
SERVE pancakes with sauce. Top with whipped cream and nuts.