Heat oven to 350 degrees F. Position an oven rack in the lowest position.
Using a piece of waxed paper, spread butter evenly over bottom and up sides of a glass 9-inch pie plate. If desired, measure out 1/3 cup of the coconut for garnish and spread it out in a cake pan for toasting later. Sprinkle remaining coconut over bottom and up sides of prepared pie plate. Gently press coconut into butter.
Bake the coconut shell on the bottom rack in 350 degrees F oven for 13 minutes or until rim is lightly browned (center and sides will just begin to turn light golden). Cool completely on wire rack. Toast coconut for garnish in 350 degrees F oven, stirring once or twice, for 6 minutes, until golden brown.
In a blender or food processor, puree mangoes until very smooth. There should be a scant 2 cups puree. Pour into large bowl; stir in orange juice.
Place 2 tablespoons cold water in a 1-cup glass measuring cup. Sprinkle gelatin over water; let soften for 2 minutes, then stir. Heat in microwave oven for 10 to 15 seconds to dissolve gelatin. Stir; set aside to cool for 5 minutes.
In medium-size bowl, beat cream with confectioners' sugar until stiff.
Add gelatin to mango mixture; stir well. Gently fold whipped cream into mango mixture until no white streaks remain. Pour into cooled crust. Garnish with toasted coconut, if desired; refrigerate 4 hours or overnight.