Heat the oven to 325F/165C. Place the hazelnuts on a baking sheet and roast them in the oven for 10 to 12 minutes, until fragrant and light brown. Remove from the oven, cool for 5 minutes, and transfer to a food processor fitted with a blade. Pulse for a few seconds at intervals to get a fine granular powder.

Add the butter, sugar, hazelnut extract, and cinnamon. Pulse for a few seconds at intervals until the mixture gets whipped and creamy. Scrape the sides of the food processor down. Add the flour and pulse until combined; there should be no dry flecks of flour. Transfer the mixture to a medium bowl. If any dry flecks of flour are still present, mix by hand and press together to form a dough. Cover the bowl with a lid or cling film and place in the refrigerator for 30 minutes. The mixture can also be refrigerated overnight and baked the next day.

When ready to bake, heat the oven to 325F/165C. Line two baking sheets with parchment paper. Using a 1 Tbsp scoop or teaspoon, scoop out the dough into your palms and shape into small balls. Place each ball on the baking sheet, leaving about 1 in/2.5 cm space between them. Bake the cookies for 15 minutes until they start to turn a very light golden brown. Rotate the baking sheets halfway through during cooking. Remove the sheets from the oven and let the cookies cool for 10 minutes on the baking sheet; transfer to a wire rack and cool completely.

Add the remaining confectioner’s sugar to toss the cookies in a medium bowl. Work in batches. Transfer 3 to 4 cookies to the bowl and toss gently to coat well. Transfer the cookies to an airtight container and store them for up to 2 weeks. They can also be frozen for up to a month. I like to add a few tablespoons of confectioner’s sugar to the storage container to keep the cookies coated.