Preparation

1. Preheat the oven to 170°C.
2. Line two baking pans with parchment paper.

Prepare the cookie dough

1. Cream the butter in a mixing bowl using a spatula.
2. Add in sugar and mix. Then continue to mix using a hand held mixer at medium speed until pale and fluffy.
3. Mix in egg yolks, double cream and vanilla extract and continue to beat until well combined. Scrape down the sides and the bottom of the bowl if needed.
4. Sift in cake flour, corn flour and sea salt.
5. Mix using a spatula first then with a hand held mixer until just combined.
6. Divide the dough in half using a kitchen scale for accuracy.
7. Mix the cocoa powder into one half to create chocolate dough.

Pipe the cookies

1. Place each flavour into a separate piping bag.
2. Cut a hole at the top of a new piping bag and insert an open star piping tip.
3. Cut a hole at the top of the vanilla dough bag. Place it into the bag with piping tip.
4. Start piping on a lined baking pan in a circular motion to create a swirl-shaped cookie. Continue to pipe spaching each cookie an inch apart.
5. Swap the vanilla dough bag with the chocolate dough bag and continue to pipe the cookies onto a lined baking pan.
6. Place the piped cookies in the freezer until they firm.

Bake and Cool the cookies

1. Bake the cookies in a preheated oven for about 18 to 20 minutes or until the edges turn golden brown.
2. Remove the cookies from the oven and let them sit on a baking pan for around 5 to 10 minutes.
3. Transfer them on a wire rack to cool completely.
4. Serve them with a cup of coffee. Enjoy!