For the Cookie Dough

1. Cream butter and sugar: In a large mixing bowl, or a stand mixer bowl, cream together: 1 cup softened butter and 1 cup granulated sugar
2. Add egg and vanilla: Add one room temperature egg, 1 teaspoon vanilla to the butter and cream mixture
3. Sift dry ingredients: 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. Combine wet and dry: Gradually combine the dry ingredients with the wet ingredients until a soft dough forms
5. Shape and chill dough: 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 oven: Preheat oven to 350°
7. Roll out dough: Soften refrigerated dough at room temperature about 30 minutes, then roll the dough out to about 1/8 inch
8. Cut cookies: Cut out using a 1½ inch cookie cutter
9. Arrange on sheet: Arrange on a baking sheet about 1 inch apart
10. Bake: Bake for 9-10 minutes and allow to cool completely

For the Fondant Creme Filling

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