Step 1

Preheat the oven to 375 degrees F, and line baking sheets with parchment paper.

Step 2

In a large mixing bowl, beat the sugar and butter together on medium speed, until smooth (about 1 minute).

Step 3

Scrape the bottom and sides of the bowl with a silicone spatula, and mix in the in the egg and vanilla.

Step 4

Add the dark cocoa powder, cornstarch, and salt, and mix on low speed to combine.

Step 5

Add the flour, a little at a time, until the dough forms a ball and pulls cleanly away from the sides of the bowl (you might not need all the flour*).

Step 6

Roll out the dough between two sheets of parchment paper, to a thickness of 1/4-inch (rolling pin rings will help you to get an even thickness).

Step 7

Use a 2-inch diameter fluted round cutter to cut shapes, place on the prepared baking sheets, and bake until crisp around the edges and set in the centers (approx. 9 to 12 minutes).

Step 8

Cool completely, and sandwich with creme filling.

Step 9

In a large mixing bowl, beat the powdered sugar, cream cheese, vanilla, and salt together until smooth.