In a medium size bowl stir the butter until creamy and smooth. Add the sugars and stir again until well combined. Add the egg and both extracts and stir again.
Next add the cocoa powder, corn starch and salt. Stir until completely incorporated.
Lastly, add the flour and stir, from the bottom up, scraping the sides of the bowl until the flour is mixed in and there are no white streaks. At first, it will seem like too much flour. Just keep going and suddenly it will all come together.
Turn the dough out onto a lightly floured surface and knead a few times to bring the dough together. Divide the dough in half.
Working with one half at a time, roll the dough on a lightly floured surface, lifting it several times to another area to keep it floured underneath. If your rolling pin is sticking, you can lightly flour it but brush off any excess flour to avoid any white flour on the dark surface of the cookies.
Using a cutter of your choice, cut as many shapes as you can from the rolled out dough and transfer them to a prepared pan. At this point, you can place the cookies close together on the pan until after chilling them.
Re-roll scraps then repeat the rolling and cutting with the second portion of dough. Place the cutout cookies in the refrigerator for at least 1 hour (longer is fine).
Preheat the oven to 350˚F. Bake the cookies for 10-12 minutes until slightly firm to the touch. Larger cookies will take a bit longer.
Transfer the baked cookies to a cooling rack and allow to cool completely before adding the almond buttercream.