01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, oats, cinnamon, nutmeg, baking soda, and salt until evenly mixed.
03 - In a large bowl, beat softened butter with granulated and brown sugars until light and fluffy.
04 - Add eggs one at a time to the creamed mixture, beating well after each addition, then mix in vanilla extract.
05 - Gradually add the dry ingredients to the wet mixture, stirring until just combined without overmixing.
06 - Gently fold raisins and toasted hazelnuts into the dough until evenly distributed.
07 - Drop tablespoon-sized portions of dough onto prepared baking sheets, spacing them approximately 2 inches apart.
08 - Bake in preheated oven for 10 to 12 minutes, until cookies are golden at the edges and set in the center.
09 - Let cookies cool on baking sheets for 5 minutes before transferring to a wire rack to cool completely.
10 - In a small microwave-safe bowl, combine chocolate-hazelnut spread and heavy cream. Heat in 10-second intervals, stirring until smooth and pourable.
11 - Drizzle the hazelnut mixture over cooled cookies and allow to set before serving.