For the meringue: Beat egg whites until stiff peaks, then whisk in sugar 1tbs at a time. Gently fold in the vinegar. Spoon onto greaseproof paper on a tray. Put into the oven and turn down to 150ºC immediately, then bake for about 45 mins. Should be hard on the outside, chewy in middle.
For the filling: Whip the cream and creme fraiche together and slice the bananas, fold half through the cream mix together with half the meringue (broken up).
For the sauce: Put all sauce ingredients in a pan and boil until combined, allow to cool.
To serve put a spoonful of the creamy mix in a cocktail glass, then some meringue, muesli, banana and a swirl of sauce, repeat, taking the mix above the top of the glass, finish with meringue, banana and lots of sauce, then top with more muesli.