01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, baking soda, and salt. Set aside.
03 - In a large bowl, beat the butter, granulated sugar, and brown sugar until light and fluffy, about 2–3 minutes.
04 - Add eggs one at a time, beating well after each addition. Mix in the vanilla extract.
05 - Gradually add the dry ingredients to the wet, mixing until just combined.
06 - Fold in the chocolate chips and chopped toasted hazelnuts.
07 - Scoop tablespoon-sized balls of dough onto the prepared baking sheets, spacing them about 2 inches apart.
08 - Bake for 10–12 minutes, or until the edges are golden but centers are still soft. Cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.
09 - For the drizzle, melt chocolate chips and hazelnut spread together in a heatproof bowl over simmering water or in the microwave in 20-second bursts, stirring until smooth. Stir in coconut oil if using.
10 - Drizzle the chocolate hazelnut mixture over the cooled cookies. Allow the drizzle to set before serving.