Step #1 In a bowl, beat the sugar into the eggs until thickened & pale yellow; beat in the flour & salt; set aside.
Step #2 Bring milk to a boil in a pan; slowly beat the hot milk into the egg/sugar mixture.
Step #3 Pour the entire mixture back into the pan & place over low heat/flame.
Step #4 Stir constantly with a whisk or wooden spoon until the custard thickens slightly; be careful not to let the mixture boil or the eggs will scramble.
Step #5 Remove pan from heat & pour hot custard through a strainer into a large, clean bowl.
Step #6 Mash the bananas with a fork until they are creamy (or puree them in a food processor/blender).
Step #7 Add the banana puree to the hot custard; mix well.
Step #8 Allow the banana custard to cool slightly; stir in the the cream, vanilla, & liqueur.
Step #9 Cover up & put in the fridge until cold or overnight.
Step #10 Stir the chilled custard, then freeze in 1 or 2 batches in your ice cream maker according to manufacturer’s directions.
Step #11 When finished, the ice cream should be soft but ready to eat; for firmer ice cream, transfer to a freezer-safe container & freeze several hrs or overnight.