Heat oven to 350°F. Line 2 large cookie sheets with parchment paper.
Let cookie dough stand at room temperature 10 minutes to soften. In large bowl, break up cookie dough. Add frosting, oats and 1/8 teaspoon salt. Beat with electric mixer on medium speed until well blended. Working with 1/2 of the dough; drop by tablespoonfuls to make 24 cookies. Place 3 inches apart on cookie sheets. (Cookies will spread.)
Bake 2 cookie sheets at a time, 10 to 14 minutes or until golden brown, turning cookie sheets halfway through bake time. While cookies are baking, drop remaining tablespoonfuls of dough onto parchment paper to make 24 additional cookies. Remove baked cookies and parchment paper to cooling rack. Cool completely, about 10 minutes. Repeat with remaining dough and parchment paper.
Spread 1 heaping teaspoon of the hazelnut spread onto bottom of 24 cookies. Top with remaining cookies bottom side down; press lightly. Store in covered container.