In a medium saucepan, set over medium heat, whisk together the half and half, granulated sugar and salt. Heat until just warmed through, to about 175 degrees F. Whisk the eggs in a large bowl, and slowly stream in the warmed half and half mixture, while whisking constantly. Once all have been added, pour the mixture back into the pot and return to the heat. Cook stirring nonstop, over low heat, until the mixture reaches 160 degrees F and coats the back of a wooden spoon.

Remove from the heat and place the bottom of the pan into a bowl of cold water filled with ice. This will help cool the mixture quickly. While the saucepan is on the ice water, stir it for about 2 minutes to help it along. Remove from the ice bath, and stir in the heavy cream, evaporated milk and vanilla. Cover the top with plastic wrap, making sure the plastic touches the surface of the custard. Then cover the bowl tightly with another piece of plastic wrap. Refrigerate until chilled through, for several hours or overnight.

When ready to churn, mash the bananas in a medium bowl, until fully smooth. Stir into the custard. Alternatively, you can blend the bananas with a bit of the custard in a blender or food processor until smooth, and then whisked back into the remaining custard. Pour into your ice cream maker and churn according to the manufacturer's directions. Once thickened and frozen, turn the machine off.

To layer assemble the ice cream, pour a bit of the banana ice cream into several freezer safe containers (or one large one), and then layer with a bit of the whipped topping, and crushed wafers. Then layer with another bit of ice cream and repeat with the whipped topping and wafers, until all the ingredients are used up. Cover tightly and freeze until firm, about 2 to 4 hours. Scoop out into bowls or cones and enjoy!