Cookies: Preheat the oven to 350 degrees F and position the rack to the center position. Dust the work surface with flour. Place the dough on the table and dust with flour. With a rolling pin, work the dough, rolling back and forth. After 3 rolls, stop and move the dough around (you don't want it to stick to the work surface). Dust with additional flour and continue to roll until it is 1/2-inch thick. Cut out 6 (3-inch) circles and 12 bat-wing shapes, gathering the scraps and rerolling as necessary. Place on a parchment lined cookie sheet. Bake for 12 to 15 minutes. Remove from the oven and cool to room temperature.
Batty Chocolate Mousse: Chop up the chocolate very fine and place in a heatproof bowl. In a small saucepan bring 1 cup of the cream to a boil. Remove from the heat and pour the cream over the chocolate. Let sit for 1 minute. Then, whisk together until smooth and set aside and cool.
Whip the remaining 1 cup of the heavy cream to soft peaks. Fold the soft whipped cream into the chocolate mixture. Spoon into 6 (3-inch) dome molds. Schmear with a spatula across the top and top with a cookie disk. Place in the freezer for at least 4 hours.
Chocolate Glaze: Chop the chocolate into 1/4-inch fine pieces and place in a medium size mixing bowl with butter. In a small saucepot over medium flame, bring the sugar and water to a boil, stirring to combine. Pour the sugar syrup over the chocolate and stir until smooth.
Assembly: Unmold onto a wire rack. Place the rack on a parchment-lined sheet tray. Pour over the chocolate glaze. Stick 2 wing cookies in the side of each dome. Serve immediately or refrigerate for up to 2 days.
Traditional Cookie Dough
Sift together the flour, baking powder, and salt in a medium bowl and reserve. Place the butter in a large mixing bowl and soften by hand. Add the sugar and continue to blend with hands or a rubber spatula for 2 minutes, until the mixture resembles light yellow-colored mashed potatoes. Transfer to a mixer.
Crack the eggs, 1 at a time, into the butter mixture and combine until well blended. Add the vanilla extract. Add the sifted flour mixture and continue to blend for 2 to 3 minutes until a dough is formed. Remove dough from the mixer and divide in half. Place 1/2 of the dough back into the mixer. On low speed, add the cocoa powder and continue to mix until you have a chocolate dough. Wrap both doughs in plastic wrap and refrigerate for at least 1 hour, up to overnight. Use chocolate dough for the Batty Chocolate Mousse recipe and the plain dough for the Witches Finger Cookies.