The trick is the filling (the banana stuff). The casing is simple. Just get a pack of shortcrust pastry sheets, use a 3 inch cookie cutter, put the cut rounds into something like this:
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Poke the bottoms a bit, and then bake in an oven till the pastry is done. Or you could do it even simpler: just go to the shops and get a pack of pack of pre-cooked tart shells. But they are much more expensive than the sheets.
Side note for suzer: you can get the above baking tray at Coles, they're around 6 dollars and last forever.
Now for the filling!
Firstly, make LOTS. This stuff is so good you'll be eating it by itself. The riper the banana is the better it tastes. Even the ones that are totally black on the outside are great to use.
For every pound of banana, you'll want 1 and 1/2 cups of sugar plus the juice of one lemon.
What do you do? Chop up your bananas (peel 'em first), and toss them, the sugar, and the lemon juice in a saucepan. Heat it up, stir FREQUENTLY. Keep it at a temp that's just bubbling the mixture. When it starts to a light orangish/reddish colour, then it's done (15 to 20 mins, the riper the banana the quicker it cooks).
Pour/spoon into a bowl and let it cool. Once it's cool, spoon it into the cooked pastry shells. Then eat! You can top them with whipped cream, that's good too.
The banana filling can be used for many things: ice cream topping, a spread on toast, filling in a flaky buttermilk biscuit, or just eat it as is. When I buy bananas I'll hide 5 or 6 of them and let them go black; THEN they are great for making the filling.