HEAT oven to 350 degrees F. Line 12 muffin cups with paper liners. Whisk together flour, hazelnuts, baking powder and salt in small bowl. Beat butter, sugar and vanilla in large bowl with electric mixer at medium speed until light and fluffy. Add eggs, one at a time, beating well after each addition. With mixer on low speed, add half the flour mixture, milk and remaining flour mixture, mixing after each addition just until blended.
DIVIDE batter evenly among muffin cups. Bake 20 to 23 minutes or until toothpick inserted in center comes out clean. Cool in pan 5 minutes. Remove to wire rack to cool completely.
WHISK instant pudding and half-and-half in large bowl. Chill for 30 minutes. Melt chocolate hazelnut spread and white baking chips in medium saucepan over low heat. Stir constantly until smooth. Remove from heat.
REMOVE paper liners from cupcakes. Cut cupcakes in half crosswise using a serrated knife. Spread about 1 tablespooon filling on bottom halves. Gently frost tops with chocolate hazelnut frosting. Place frosted tops over filling and press gently. Let rest for 30 minutes or until chocolate is set.