Directions

1. Melt chocolate with 1 cup butter (2 sticks) in a saucepan over medium-high heat, stirring constantly. Let cool slightly.
2. Put eggs, vanilla, and granulated sugar in bowl of an electric mixer fitted with the paddle attachment. Mix on medium speed until pale, 4 to 5 minutes. Mix in chocolate mixture, salt, cinnamon, 1/2 cup cocoa powder, and the flour.
3. Heat a waffle iron until hot. Lightly coat grids with cooking spray. Spoon about 1 tablespoon batter onto center of each waffle-iron square to make 1 1/2-inch rounds. Close cover; cook until set, about 1 1/2 minutes. Transfer to a wire rack, bottom sides up. Let cool completely. Repeat with remaining batter, coating grids with cooking spray after each batch.
4. Melt remaining 2 tablespoons butter in a small saucepan over low heat. Add confectioners' sugar and remaining 2 tablespoons cocoa powder; stir until smooth. Stir in milk.
5. Gently dip 1 surface of each cookie in icing so that just the waffle lines (not gaps) are coated. Repeat with remaining cookies and icing. Transfer to wire racks; let stand until set, about 10 minutes. Dust iced surfaces of cookies with confectioner's sugar. Cookies can be stored in single layers in airtight containers at room temperature up to 2 days.