Chocolate Gingerbread House Petits Fours

INGREDIENTS

• 1 1/2 cups boiling water
• 1 1/2 teaspoons baking soda
• 3 1/4 cups all-purpose flour, plus more for dusting
• 3/4 cup unsweetened cocoa powder, preferably Dutch-process
• 4 teaspoons ground ginger
• 4 teaspoons ground cinnamon
• 1 teaspoon freshly grated nutmeg
• 3/4 teaspoon ground cloves
• 1 teaspoon salt
• 1 tablespoon baking powder
• 10 tablespoons (1 1/4 sticks) unsalted butter, room temperature, plus more for pan
• 1 cup packed dark-brown sugar
• 1 1/2 cups unsulfured molasses
• 3 large eggs, room temperature
• About 1 1/2 cups chocolate frosting
• 2 red licorice wheels, unwound and cut into 50 pieces (3/4 inch each)
• Confectioners' sugar, for dusting