In a bowl, cream butter & powdered sugar together; add flour, cocoa & 1/4 tsp flavoring; mix well.
Green & Beige Cookie Dough
In a bowl, whisk together cornstarch, powdered sugar & flour. Blend in butter & flavoring with a fork, mixing until a soft, smooth dough forms. Divide dough in half & add enough green coloring to ONE portion to give it a kiwi color.
Assembly
Roll out the chocolate dough between parchment paper in a rectangle shape about 5 X 10-inches & about a 1/8-inch thickness. Next, roll out the green dough between parchment paper in a rectangle about 3 X 10-inches & about 1/4-inch thickness. With the beige colored dough, roll out to 10-inches long & form into a round ‘log’ for the center of cookies on parchment paper.
Now top the chocolate layer with green layer. Place cylinder of beige dough at one side. Using the help of the parchment paper, roll together, starting at even end & roll to end with the extended chocolate, so that the chocolate goes all the way around. Wrap tightly in plastic wrap & refrigerate about an hour or freeze until ready to use.
Preheat oven to 300 F. When chilled, unwrap & cut slices 1/3-inch thick. Line a baking sheet with parchment paper; place slices about an inch apart. With the tip of a knife, make a kiwi pattern in center of cookies & arrange black chia seeds. Bake for about 20 minutes. Do NOT brown. Allow to cool on baking sheet a couple of minutes then place on a cooling rack.