Use the paddle attachment to beat the cold cubed butter and sugar until soft, fluffy, and pale. Scrape the sides to make sure everything is well-mixed. Because the butter is cold, the mixture may look uneven and lumpy, but keep beating it until it becomes smooth and light in colour.
1 cup Granulated sugar, ¾ cup Butter
Add the egg, vanilla, and almond extract and mix. The mixture will look broken, and that's okay. Keep beating until smooth. Use a kitchen scale to measure exactly half the mixture. We must mix the dry ingredients in two bowls—one for the vanilla cookie dough and one for the chocolate cookie dough.
1 Egg, 1 teaspoon Vanilla extract, ½ teaspoon Almond extract
Sift the plain (without cocoa powder) dry ingredients into half the butter mixture and gently mix. Set aside.
1¼ cup All-purpose flour, ¼ teaspoon Baking powder, ¼ teaspoon Salt
Sift the dry ingredients with the cocoa powder into half the butter mixture. Add the heavy cream and mix gently. Set aside. Shape each cookie dough into a rectangular shape.
1 cup +1 tablespoon All-purpose flour, ¼ teaspoon Baking powder, ¼ teaspoon Salt, ¼ cup Cocoa powder, 2 tablespoon Heavy cream
Place each cookie dough between two pieces of parchment paper and roll out to about 9X13 inches and ⅛ inch thickness. You will have two squares of vanilla and chocolate cookie dough sheets.
Remove the top paper from the vanilla dough and the bottom paper from the chocolate dough. Place the chocolate sheet over the vanilla sheet. The parchment paper is still under the vanilla dough and on the chocolate dough. Use the rolling pin to gently go over the dough sheets only two to three times. This will stick the cookie sheets together.
With the longer side of the rectangle towards yourself, roll the dough tightly in a jelly-roll style. You will have a log about 8 to 10 inches long. Wrap the log in cling wrap and chill it in the fridge for one hour.
Preheat the oven to 350℉ and line a baking sheet with parchment paper. Make sure the log is thoroughly chilled. Cut the log into ¼ inches thick and place them on the lined baking sheet, leaving some gaps between them. Bake the cookies for 10-12 minutes. Let them cool down on the sheet, then transfer to the cooling rack to cool down completely.