Preheat oven to 375°F. Melt 2 ounces of the chocolate as directed on package. Set aside. Coarsely chop remaining 4 ounces chocolate. Mix flour, baking powder and salt in small bowl.
Beat butter, chocolate-hazelnut spread and sugars in large bowl with electric mixer on medium speed until light and fluffy. Add eggs and vanilla; mix well. Add melted chocolate; beat until well blended. Gradually beat in flour mixture on low speed until well mixed. Stir in chopped chocolate.
Drop by rounded tablespoons or medium cookie scoop 1 1/2 inches apart on baking sheets sprayed with no stick cooking spray or lined with parchment paper.
Bake about 10 minutes or just until cookies are set and slightly cracked on top. Cool on baking sheets 1 minute. Remove to wire racks; cool completely.