Preheat Oven and Prepare Baking Sheet: Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
Zest and Sugar: In a large mixing bowl, combine the granulated sugar and orange zest. Rub the zest into the sugar with your fingers until the sugar is fragrant and moist.
Combine Wet Ingredients: To the sugar-zest mixture, add the olive oil, eggs, and vanilla extract. Using a hand mixer or a stand mixer, beat until well combined.
Add Dry Ingredients: Gradually add the dry ingredients to the wet mixture, mixing until just combined. Fold in the toasted and chopped hazelnuts.
Shape Cookies: Use a cookie scoop or spoon to drop dough onto the prepared baking sheet, spacing them about 2 inches apart.
Bake: Bake in the preheated oven for 12-15 minutes, or until the edges are lightly golden and the tops are set.
Cool: Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.
Optional Glaze: If using, whisk together the powdered sugar and orange juice until smooth. Drizzle over the cooled cookies.
Serve: Enjoy the cookies as is or with the optional orange glaze for an extra hit of sweetness and citrus flavor.