Heat oven to 350 degrees F. Grease 13 x 9 x 2-inch baking pan.
Heat evaporated milk, brown sugar and butter in small saucepan over medium heat until mixture is melted and smooth. Stir in coconut and pecans; remove from heat. Spread mixture evenly over bottom of prepared pan.
Beat together cake mix, water, coffee-flavored liqueur, eggs and cinnamon in large bowl at medium speed until blended, for about 2 minutes. Spoon batter evenly over mixture in pan.
Bake in 350 degree F oven for 35 to 40 minutes or until wooden pick inserted in center comes out clean. Cool cake in pan on rack 20 minutes. Invert on platter; remove pan. Let cool completely, 40 minutes.
Place melted chocolate in small plastic bag. Snip hole in bottom corner of bag. Drizzle chocolate over cake in zigzag design. Lightly sprinkle with toasted coconut if desired. Cut into squares. Makes 16 servings.