Preheat oven to 350°F. Line cookie sheet with parchment paper.

In medium bowl, combine flour, sugar, baking powder and salt; mix well. Chop 1/2 cup Candy Melts candy; reserve remaining.

In large bowl, beat eggs, butter and vanilla with electric mixer until well combined. With electric mixer on low speed, add flour mixture to egg mixture 1 cup at a time, scraping bottom and sides of bowl as needed; mix until just combined. Beat in 1/2 cup chopped Candy Melts candy and hazelnuts. On lightly floured surface, pat into a 12 in. x 4 in. log; place in middle of prepared cookie sheet.

Bake 25 to 28 minutes or until firm to the touch. Cool log 30 minutes on cookie sheet. Slice into 1/2 in. thick pieces with serrated knife. Place slices cut side up on cookie sheet. Reduce oven temperature to 300°F. Bake cut biscotti 10 minutes; flip biscotti and bake an additional 10 minutes or until firm. Cool completely on cookie sheet.

Melt remaining Candy Melts candy according to package instructions. Dip bottoms of biscotti in melted candy. Place on parchment-lined cookie sheet until set, 5-10 minutes.