BEAT 1 3/4 cups cookie mix, peanut butter, 3 tablespoons melted butter, 1 egg and vanilla in medium bowl with electric mixer on medium speed until blended.
STIR flour, salt and remaining cookie mix in a separate medium bowl until blended. Add chocolate hazelnut spread, remaining 3 tablespoons melted butter and 1 egg. Beat with electric mixer on medium speed until well blended. (Dough will be stiff.) Divide both peanut butter dough and chocolate hazelnut dough in half to make 4 parts. Roll each part between 2 sheets of wax paper to make four 10 x 8-inch rectangles. Stack flat layers of wrapped dough on top of each other on baking sheet. Chill 15 minutes.
REMOVE top sheets of wax paper from sheets of dough. Turn one peanut butter layer upside down onto one chocolate hazelnut layer, aligning corners. Remove wax paper from peanut butter layer. Allow dough to soften slightly, about 3 minutes. Beginning on one long side, roll up dough to make a log, making sure the center is rolled tightly with no air pockets. Roll wax paper around log. Repeat with remaining 2 sheets of dough. Freeze 1 hour.
HEAT oven to 375 degrees F. Cut logs into 1/4-inch slices. Place on ungreased baking sheet. Bake 7 to 8 minutes or until just lightly browned. Cool on baking sheet 2 minutes. Remove to wire rack to cool completely.
Spread peanut butter and/or chocolate hazelnut spread in a thin layer on bottom side of half the cookies. Place another cookie, bottom side down, on top of peanut butter layer to make sandwich cookies. Makes 3 dozen.