Put the caster sugar and 2 tablespoons water in a saucepan and cook over a medium heat, stirring, for 30 seconds–1 minute or until the sugar has dissolved. Bring to the boil over a high heat and boil for 4–5 minutes until the syrup has turned a medium caramel colour. Remove from the heat and stir in 6 tablespoons of the cream, being very careful as it may sputter a bit.
Return the pan to a low heat and cook, stirring, for 1–2 minutes until any hard lumps of caramel have dissolved, then keep warm over a very low heat.
Put the remaining cream in a large bowl and whip, using an electric mixer, until soft peaks form. Peel and slice the bananas.
Put the meringue nests on four plates and spoon the whipped cream over them. Top with the banana slices, drizzle with the sauce and serve. Alternatively, crumble the meringues into four glasses, layer with cream, bananas and sauce and serve.