Sift together the flour, baking powder, salt, and instant coffee in a bowl. Set aside.

In a mixer bowl, combine cocoa powder, sunflower oil, and sugar.

Using the flat beater attachment (K-beater), mix until well combined, scraping down the sides as needed.

Add the eggs one at a time, mixing thoroughly after each addition until the batter is smooth.

Mix in the vanilla sugar or extract for extra flavor.

Gradually add the sifted flour mixture in small portions while mixing. Avoid overmixing to maintain the dough’s texture. Scrape the sides to ensure the mixture is uniform.

Cover the bowl with cling film and refrigerate for at least 4 hours, or overnight for easier handling.

After chilling, take the dough out and shape it into walnut-sized balls using lightly floured hands.

Roll each ball generously in sifted powdered sugar to coat.

Place the coated balls on a baking tray lined with parchment paper.

Preheat the oven to 175°C (350°F). Bake the cookies for 10–12 minutes (adjust for your oven type; fan ovens may require less time).

Allow the cookies to cool slightly before transferring them to a wire rack. Once completely cooled, store them in an airtight container.