01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the flour, baking soda, salt, and cinnamon. Stir in the oats evenly.
03 - In a large bowl, beat the softened butter with the brown and granulated sugars until light and fluffy.
04 - Beat in eggs one at a time, ensuring each is fully incorporated, then mix in the vanilla extract.
05 - Gradually add the dry ingredients to the wet mixture, stirring just until combined to avoid overmixing.
06 - Fold the raisins and chopped toasted hazelnuts gently into the dough.
07 - Scoop heaping tablespoons of dough onto the prepared baking sheets, spacing each about 2 inches apart.
08 - Bake for 10 to 12 minutes until edges turn golden and centers appear set.
09 - Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.
10 - In a small microwave-safe bowl, combine the hazelnut spread and heavy cream. Heat in 10-second intervals, stirring until the mixture is smooth and pourable.
11 - Drizzle the hazelnut mixture over cooled cookies. Optionally garnish with additional chopped hazelnuts and allow the drizzle to set before serving.