01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - Whisk together flour, baking soda, and salt in a medium bowl; set aside.
03 - In a large bowl, beat butter with brown and granulated sugars until creamy and light, about 2 to 3 minutes.
04 - Add eggs one at a time, beating well after each addition, then mix in vanilla extract.
05 - Gradually add dry ingredients to the wet mixture, stirring until just combined.
06 - Fold in semisweet chocolate chips and chopped toasted hazelnuts evenly.
07 - Scoop tablespoon-sized portions of dough onto prepared baking sheets, spacing them 2 inches apart.
08 - Bake for 10 to 12 minutes until edges are golden and centers set.
09 - Remove from oven; cool on baking sheets for 5 minutes before transferring to wire racks to cool completely.
10 - Combine chocolate-hazelnut spread and milk in a microwave-safe bowl, heating in short bursts until smooth. Drizzle over cooled cookies with a spoon or piping bag.
11 - Allow drizzle to firm before serving.