Instructions: In a medium bowl, mix flour, cocoa, baking soda, baking powder and salt thoroughly with a whisk or fork. Set aside.

In a large bowl, beat butter and sugars with back of a spoon or mixer until smooth and creamy but not fluffy (less than 1 1/2 minutes with an electric mixer). Mix in egg and vanilla. Add flour mixture and mix just until incorporated. Form dough into log about 6 inches long and 2 1/2 inches wide.

Chill at least 3 hours, preferably overnight.

Position racks in upper and lower third of oven and preheat to 350 degrees.

Line cookie sheets with parchment paper or foil.

Using a sharp knife, cut log into slices 1/4 inch thick. Place slices 1 1/2 inches apart on sheets. Bake until cookies have puffed and settled down again, rotating sheets from top to bottom and front to back halfway through baking, 10-12 minutes.

Do not detach cookies. Cool 3-5 minutes, then cut and remove a 1 inch circle from center of each cookie, using a 1 inch cutter. Slide parchment onto cooling racks or set cookie sheet on a rack to cool completely. Transfer cooled cookies to a clean sheet of parchment.

Make caramel by combining sugar, water and cream of tartar in a 3- to 4 cup saucepan. Stir gently (do not whisk) over medium heat until most of sugar looks dissolved. Stop stirring and bring mixture to a simmer. Cover and simmer 2 to 3 minutes to dissolve sugar. Uncover and wash down insides of pot with a wet pastry brush or a wet wad of paper towel. Continue to simmer until syrup begins to color, 10-15 minutes. Swirl pot (dont stir) if syrup seems to be coloring unevenly. Use a skewer to drop a bead of syrup on a white plate. When drop looks pale amber on the plate, pay close attention. Continue to cook and test drops of syrup until darkened to a slightly reddish amber color. Immediately remove from heat.

Spoon a little caramel carefully into center of each cookie. Set aside to cool and harden. Store cookies airtight. (Note: To clean hardened caramel from pot or plate, soak in very hot water.)

If you would like to email yourself the recipe for later use, or share the recipe with your friends or family, enter the email addresses below and this recipe will be emailed to you and others as well.