1. In a large mixing bowl, or a stand mixer bowl, cream together: 1 cup softened butter and 1 cup granulated sugar
2. Add one room temperature egg, 1 teaspoon vanilla to the butter and cream mixture
3. In a medium sized bowl, sift together: 1 ¾ cups all-purpose flour, ⅔ cups black cocoa powder, ½ teaspoon baking powder, ¼ teaspoon baking soda, and ¾ teaspoon salt
4. Gradually combine the dry ingredients with the wet ingredients until a soft dough forms
5. Form the dough into a smooth ball, then divide in half and flatten to form 2 discs. Wrap in plastic and refrigerate for about 1 hour
6. Preheat over to 350°
7. Soften refrigerated dough at room temperature about 30 minutes, then roll the dough out to about 1/8 inch
8. Cut out using a 1½ inch cookie cutter
9. Arrange on a baking sheet about 1 inch apart
10. Bake for 9-10 minutes and allow to cool completely

For the Fondant Creme Filling

1. Cream together: ½ cup unsalted softened butter and ¼ cup shortening
2. Slowly add 2 cups powdered sugar until well mixed
3. Finally, mix in ½ teaspoon clear vanilla extract and ⅛ teaspoon salt
4. Transfer filling to a pastry bag fitted with ½ inch tip
5. Pipe about 1 tablespoon of filling to the center of the bottom side of a cookie wafer, then sandwich using another cookie