Combine the very ripe bananas and eggs, mashing the bananas well. The mixture will become a bit frothy. Set aside.
In a large saucepan, combine sugar, cornstarch, salt and chosen milk until smooth. Cook and stir over medium-high heat until thickened and bubbly. Reduce heat; cook and stir 2 minutes longer. Remove from heat.
Stir a small amount of hot filling into banana/egg mixture; return all to pan.
Pour about two teaspoons of instant tapioca, stir, and bring all ingredients to a gentle boil; cook and stir 2 minutes longer until mixture thickens a bit more.
Remove from heat. Gently stir in ghee and vanilla until incorporated. Transfer to a bowl set over ice to cool down quickly. Press plastic wrap onto surface of custard; refrigerate, covered, 30 minutes to an hour.
Spread half of the custard into vanilla wafer shell. Slice extra bananas, if desired, and arrange over filling. Pour remaining custard over bananas. Refrigerate 6 hours or overnight until set. Enjoy!