Minty Chocolate Sandwich Cookies
1 cup unsalted butter, at room temperature
1 cup powdered sugar
1 tsp vanilla extract
1 cup non-alkalized cocoa powder
1 egg white
3/4 tsp salt
1 1/2 cups whole-wheat pastry flour
Peppermint cream filling:
2+ cups powdered sugar, sifted
10 - 15 drops peppermint extract (to taste)
1/4 cup half and half (or water if you are going to keep the cookies around unrefrigerated for a while)
Preheat the oven to 350 degrees F, position the racks in the middle of the oven, and line two baking sheets with parchment paper or a Silpat.
Using a stand mixer or handheld mixer, cream the butter until light and fluffy. Add the powdered sugar and cream some more, scraping the sides of the bowl a time or two. Stir in the vanilla extract, cocoa powder, egg white, and salt and mix until the cocoa powder is integrated and the batter is smooth and creamy and the consistency of a thick frosting. Add the flour and mix just until the batter is no longer dusty looking. It might still be a bit crumbly, and that's okay.
Turn the dough out onto a floured work surface, gather it into a ball, and knead it just once or twice to bring it together into a smooth mass. Divide into two pieces place each into a plastic bag and flatten into disks roughly 1 inch thick. Put the dough in the freezer for 20 minutes to chill.
One bag at a time remove the dough from the freezer. On a well floured surface roll it out very thin (remember these are going to be sandwich cookies) - roughly 1/8 inch thick. Or you might find it easiest to roll it out between to Silpats or pieces of plastic.
Use cookie cutters to cut cookies in whatever shape you like - I used tiny scalloped circles here. Place on the prepared baking sheets, and bake for 7-10 minutes. Remove from the oven and cool completely on a wire rack (if you have one).
While the cookies are baking, go ahead and make the filling. Using a stand mixer or handheld mixer, whisk together the sugar and cream (or water) until nice and fluffy. You want the filling to be thick enough that it doesn't ooze out the sides of the cookies after they are filled, so if you need to add more powdered sugar, do so in small increments. If you need to thin out your filling, add more half and half a few drops at a time. Whisk in the peppermint extract a bit at a time, and taste as you go, the peppermint flavor shouldn't be overwhelming.
When the cookies have completely cooled slather a bit of filling on half of the cookies. Top each slather with another cookie and enjoy!
Instead of minty cream filling, you can substitute strawberry, raspberry, orange, coffee or any other flavouring that you like with chocolate.