Preheat oven to 350°F. Grease and flour a 9 x 13 inch baking pan. In a medium bowl, mix together 1 and 3/4 cup flour and powdered sugar. Cut in cold butter with a pastry blender until the mixture resembles coarse crumbs. Press the mixture into the bottom of the baking pan. Bake for 8-9 minutes or until the crust is lightly browned. Let cool.
While the crust is in the oven, beat together eggs and granulated sugar. Stir in lemon juice and 1 1/2 cups of mango puree. Last, gently stir in 1/2 cup flour. Pour mixture over the cooled crust.
Reduce heat in the oven to 325 F and bake for 22-25 minutes or until set. Let cool and refrigerate at least 2 hours before cutting bars. Dust with powdered sugar and sprinkle with toasted coconut.