Combine sugar, the 2/3 cup butter, coffee, the 1/4 cup coffee liqueur, eggs, melted unsweetened chocolate, and vanilla in a large mixing bowl. Beat with an electric mixer on medium speed for 2 to 3 minutes or until creamy, scraping bowl often. Reduce speed to low; add flour, baking powder, salt, and cinnamon. Beat until combined.

Drop by rounded teaspoons 2 inches apart onto greased cookie sheets. Bake in a 350 degree F oven for 8 to 12 minutes or until edges are firm. Cool on cookie sheet for 1 minute. Remove and cool on wire racks.

Spread Coffee Frosting over cooled cookies. Drizzle with melted semisweet chocolate, if desired. Makes about 60 cookies.

Coffee Frosting: Beat 3 tablespoons butter (no substitutes), 3 cups sifted powdered sugar, and 2 tablespoons coffee liqueur in a medium mixing bowl. Gradually beat in enough coffee (2 to 3 tablespoons) to make of spreading consistency.