For Cupcakes: HEAT oven to 350 degrees F. Line 24 muffin cups with paper baking cups. Prepare cake mix according to package directions using water, oil and eggs. Beat in peanut butter until smooth. Divide batter evenly into baking cups.
BAKE for 24 to 26 minutes or until toothpick inserted in center comes out clean. Cool in pans 5 minutes. Remove from pans to wire rack to cool completely.
For Frosting: BEAT shortening, butter and peanut butter in a large bowl, with an electric mixer on medium speed until smooth. Add powdered sugar, vanilla and salt. Mix slowly until combined. Beat on high for 3 to 5 minutes until light and fluffy.
SPREAD 2 teaspoons hazelnut spread on each cupcake. Place frosting in decorator bag fitted with a star decorating tip (2A). Frost cupcakes by working in a circular motion moving towards center to build up frosting, creating a swirl effect, leaving chocolate exposed. Garnish with peanuts and shaved chocolate.