Take the butter out of the refrigerator 2-3 hours ahead of time and let it come to room temperature to soften. Preheat the oven to 350°F (180°C) with the fan on. Using a stand mixer with the whisk attachment, beat the butter on high speed for 5 minutes until it turns pale. Add the powdered sugar and continue beating for another 10 minutes. The mixture will deflate a bit when you add the sugar, but it will fluff up again as you keep mixing.

The mixture should look like whipped cream at the end. Add the vanilla and the roasted almonds (make sure they have cooled). Gradually add the flour by hand, mixing with a spatula. The dough should be crumbly and not sticky. Put on gloves and shape the dough into walnut-sized balls (about 22 grams each) and arrange them in rows on a nonstick baking sheet or a baking sheet lined with parchment paper.

Press a small indentation into the top of each cookie with your finger to help hold the powdered sugar and prevent cracking while baking. Bake for 30-35 minutes, until they are a light golden color. Remove the cookies from the oven. Carefully transfer them from the baking sheet and let them cool on a wire rack. They will be very soft while warm. Once cooled, sift powdered sugar over them and dust generously.