Preheat oven to 350 degrees F. Coat 9-inch square baking pan with cooking spray.

To make Cake: Whisk together flour, baking powder, cinnamon, and salt in medium bowl.

Beat butter and sugar with electric mixer 2 to 3 minutes, or until light and fluffy, scraping down sides of bowl occasionally. Beat in eggs one at a time, then beat in vanilla extract. Continue beating on medium speed 2 minutes, or until batter mixture is smooth. Beat flour mixture into egg mixture 1/2 cup at a time until batter is smooth. Increase beater speed to medium high, and beat 5 minutes, or until batter is light in color.

Spread batter in prepared pan, and bake 30 minutes, or until toothpick inserted in center comes out clean and Cake begins to pull away from sides of pan. Place Cake in pan on wire rack to cool, and poke holes all over using fork or skewer. Cool Cake completely.

To make Tres Leches Glaze: Whisk together all glaze ingredients in small bowl. Spoon and spread over Cake, allowing Cake to soak up all liquid. Cover with plastic wrap, and refrigerate 12 hours or up to 2 days.

To serve: Sprinkle Cake with coconut, and top with mango slices. Cut into 16 squares. Store in refrigerator.