Prepare the oven: Preheat to 340°F (170°C). Line 2 baking sheets with parchment paper.
Cream the butter: In a large mixing bowl, beat the softened butter, powdered sugar, and vanilla extract for 2–3 minutes until pale, light, and fluffy.
Add dry ingredients: Sift in the flour, cocoa powder, and cornstarch in two additions. Add salt and mix just until a soft, pipeable dough forms; do not overmix.
Pipe the cookies: Transfer the dough to a piping bag fitted with a large open star tip. Pipe 2-inch (5 cm) rosettes or swirls, spacing them about 1 inch apart.
Chill: Refrigerate the piped cookies for 20–30 minutes to help them hold their shape.
Bake: Bake one tray at a time for 13–15 minutes, or until the edges look set and matte.
Cool: Allow to cool completely before serving or storing.
Video
Notes
Butter softness: Butter should be soft enough to press with a finger, but not greasy or melting. Too soft = cookies spread.
Creaming matters: Cream the butter and sugar until fluffy; this creates the delicate, airy “melt in your mouth” texture.
Piping consistency: If the dough is too firm to pipe, let it sit at room temperature, for 10-15 minutes or if needed add add 1-2 tablespoons of milk to loosen it up. If too soft, chill for extan ra 10-15 minutes.
Use a large tip: A large open star tip (such as Wilton 1M or Ateco 828/7) works best. Smaller tips make piping very difficult.
Chill time is essential: This prevents spreading and helps the cookies keep their sharp ridges.
Chocolate variation: Dip the cookies halfway in melted dark chocolate and sprinkle with crushed pistachios or sea salt.
Cocoa quality: Use Dutch-process cocoa for deeper color and richer flavor.
Storage: Store in an airtight container for up to 5 days or freeze for up to 2 months.
Watch the Video: For a better understanding of the recipe, I always recommend watching the video recipe, which includes a step-by-step guide to help you succeed.