Grind 1 to 1 1/2 tsp. pepper flakes with a mortar and pestle or spice grinder until pieces are small. Combine brownie mix, ground pepper flakes, and cinnamon in a medium bowl; whisk until well blended. Stir in eggs, oil, and water until blended. Add 3/4 cup chocolate morsels to batter; spoon batter into a lightly greased 13" x 9" pan. Bake at 350° for 28 to 31 minutes. Cool completely in pan on a wire rack.
Place 1 cup chocolate morsels and butter in a large glass bowl. Microwave at HIGH 1 minute or until melted; stir in whipping cream. Pour mixture over cooled brownies, spreading to form a thin even layer. Place remaining 1/4 cup chocolate morsels in a 1-cup glass measuring cup, and microwave at HIGH 30 seconds or until melted. Pour melted chocolate in a zip-top plastic freezer bag; snip a tiny hole in 1 corner of bag. Pipe a zigzag drizzle over iced brownies; sprinkle lightly with chile caribe flakes, if desired. Refrigerate brownies for easy cutting.