Heat oven to 350 degrees F. Line 12 muffin cups with paper baking cups. Prepare brownie mix according to package directions using oil, water and eggs. Stir in 1/2 cup of chopped hazelnuts. Fill baking cups 3/4 full.
Bake 30 to 32 minutes or until centers are set. Cool 2 minutes. Remove from pan. Cool completely on wire racks.
For Frosting: Beat shortening, butter and chocolate hazelnut spread in a large bowl, with an electric mixer on medium speed until smooth. Add powdered sugar, vanilla, salt and 1 tablespoon of milk. Beat slowly until combined. Beat on high, 3 to 5 minutes, adding an additional 1 tablespoon milk at a time until desired consistency is achieved.
Frost cupcakes by placing frosting into corner of resealable plastic bag. Cut 1/2-inch off corner of bag. Starting at outside edge, work in circular motion to build up frosting moving towards center, creating a swirl effect. Sprinkle with reserved chopped hazelnuts.
