For the caramel ripple sprinkle 100gr sugar evenly over the bottom of a heavy-duty 4-quart saucepan, set it over medium high heat and cook barely stirring only when the inner layer of sugar starts to melt, mix the liquified sugar with the crystallized sugar on top of it very gently. Don't overstir. When all of the sugar is liquified continue cooking on low stirring until the caramel is penny-bronze in color. Take off heat, slowly add 180ml heavy cream a little at a time, stirring constantly until fully incorporated. If there are any lumps of sugar left, return on medium heat and stir until completely melted. Take off heat, add a tiny pinch of salt, cool to room temperature and store in a sealed jug until ready to use.
For the milk chocolate shaves run the knife across the surface of a chocolate bar at room temperature.
For the shortbread crumbs crush the shortbread cookies into bite size chunks.
Dissolve 3tsp in 50ml whole milk, leave to rest.
In a small saucepan over medium heat combine 200ml heavy cream, the leftover milk, 80gr sugar and a pinch of salt, stir, bring to an almost boil, add the cornstarch milk and cook constantly stirring until thickened. Take off heat, add the cream cheese and fresh banana purée, stir until smooth. Cool to room temperature, then transfer into the fridge overnight.
Freeze in your ice cream maker according to the manufacturer's instructions adding the shortbread pieces and chocolate shaves at the last couple of minutes of churning. Transfer into an airtight container, swirling in pockets of the caramel sauce (use half the amount that you prepared) and store in the freezer for at least 4 hours until firm enough to scoop.