In a small sauce pan on medium low heat, gently melt butter, while attentively stirring until it reaches a deep golden brown and smells nutty. Remove from heat and transfer to a mixing bowl to cool.
Mix crushed crackers with the brown butter. Transfer to a tart or spring form pan, reserving at least 1/4 cup for the final topping in step 10. Press crumbs down to form a crust on the bottom of the pan.
Put crust in the freezer to chill for at least 1 hour.
In a blender or food processor, pulse mango until it becomes a thick purée.
Using a Kitchen Aid standing mixer or whisk, whisk the cream until fluffy.
Gently fold in the sweetened condensed milk into the whipped cream.
When the crust has chilled enough to harden, pour half of the cream mixture. Return pie to the freezer to chill for at least 1 hour.
Spread the mango purée onto the chilled pie layer. Return pie to the freezer to chill for 1 hour more.
Pour the remaining cream mixture on top of the chilled mango layer.
Top with the remainder of the brown butter crushed crackers.
Freeze for another hour or overnight. Let sit out at room temperature for about 20 minutes to thaw before cutting.
