Chocolate Sandwich Cookies with Tahini Marshmallow

TAHINI MARSHMALLOW

1. Grease a 12" x 16" baking sheet (half sheet), or jelly roll pan with neutral oil or butter. Combine the powdered sugar and corn starch and set aside. This is your "Marshmallow dust".
2. In the bowl of a stand mixer fitted with the whisk attachment, combine the cold water and gelatine. Mix well with a fork, and leave to bloom while you prepare the sugar syrup. 
3. In a medium pot, combine the water, honey, vanilla, and sugar. Heat over medium to high heat, stirring occasionally. Heat until the syrup reaches 240˚f / 120˚c, then remove from the heat and leave to cool to 210˚f / 100˚c.
4. Turn the mixer on to medium, and mix for a few seconds to help break up the bloomed gelatin. With the mixer running, VERY carefully pour the hot sugar syrup into the mixer. Turn the speed up to high, and whip for 7-10 minutes, until the marshmallow has doubled in volume, has turned white, and holds somewhat of a peak when you stop the mixer and lift out the whisk. You want to see little strands starting to form around the whisk attachment as it whips - this may seem like you have taken it too far, but you need the structure for when you add the tahini. 
5. Add the tahini, and fold in well with a spatula.
6. Working quickly, scrape the marshmallow into the prepared tin using a lightly oiled rubber spatula. Smooth the surface using an oiled offset spatula, or back of a spoon. Use wet fingers to help the smoothing process if needed. Dust liberally with the marshmallow dust. Allow to cure for 3-4 hours.
7. Carefully turn out onto a board, and dust the entire surface with the powdered sugar and corn starch mix. Using a 2 ½ inch cutter dusted with marshmallow dust, cut circles out of the marshmallow. Set aside on a plate, dusting with extra marshmallow dust if needed.

CHOCOLATE COOKIES

1. In a medium bowl, sift together the flour, cocoa, and baking soda. 
2. In the bowl of a stand mixer fitted with the paddle attachment, beat the butter on high until smooth and creamy, 2-3 minutes. Add the salt, and mix for another 30 seconds, then add the sugar and vanilla and mix for a further 3-5 minutes, until pale and fluffy. 
3. With the mixer on low (be careful not to puff flour everywhere!), add half of the dry ingredients, and mix until just combined. Add the second half, and mix until incorporated. Turn the mixture out onto a piece of plastic wrap, and bring together to form a rectangle. Wrap tightly and place in the fridge for at least an hour, or until firm. 
4. Preheat the oven to 325˚f / 165˚c, and place oven racks in the upper and lower thirds of the oven. Line two baking sheets with parchment paper. Place the rectangle of cookie dough on a sheet of parchment paper, and top with a second piece. Hit it a couple of times with your rolling pin to help flatten. Roll out the dough to approximately ⅛" thickness, then transfer to a baking sheet or board, still between the parchment paper, and place in the fridge for about 10 minutes to help it firm up. 
5. Remove the dough from the fridge and peel off the top layer of parchment. Using a 2 ½ inch cutter, cut circles from the dough, and place on the lined baking sheets, leaving about ½ an inch between. Re-roll scraps and cut more cookies if desired. Bake for 15-17 minutes, rotating once during cooking, until the cookies have firmed. Remove from the oven, allow to cool for 10 minutes on the baking sheet, then transfer to a wire rack to cool completely. 

ASSEMBLY

1. Pair up the cookies into pairs of equal size. Place a marshmallow circle between each pair of cookies. Secure with a little melted chocolate if needed. Drizzle the finished cookies with melted chocolate. Allow the chocolate to set in the fridge if needed. Store in an airtight container.