I highly recommend using Trader Joe's(R) Triple Ginger Snaps for the crust. They are the most flavorful gingersnaps I've come across. If this brand isn't available to you, try to find the strongest gingersnap cookies you can.
When selecting ripe mangoes, pick ones that are fragrant and slightly firm, but fleshy.
If you have mango extract, add some to taste when you beat in the mango puree.
To minimize cracking, place a shallow pan half full of water on lower rack during baking.