Line a 9-inch springform pan with parchment.
Leave some parchment overhang on the bottom, if possible.
Stir vanilla wafer crumbs, melted butter, brown sugar, and salt together.
Press the crumbs firmly into the bottom of the pan.
Freeze the crust for 15 minutes.
Spread softened vanilla ice cream over the crust.
Spoon 1/2 cup mango puree over the vanilla layer.
Swirl lightly with a butter knife.
Freeze for 30 minutes.
Spread softened mango sorbet over the first layer.
Sprinkle 1 cup diced mango over the sorbet.
Add the whipped topping over the mango layer.
Smooth the top with an offset spatula.
Drizzle remaining mango puree over the top.
Freeze at least 6 hours, or overnight.
Rest the cake on the counter for 8 to 12 minutes before slicing.
Dip a sharp knife in hot water before cutting.
Wipe the blade between slices.
Add extra diced mango before serving.
Add toasted coconut before serving, if using.