For the lemon curd ripple in a small saucepan whisk together the freshly squeezed lemon juice, 80gr sugar, pinch salt, eggs, egg yolks and the unsalted butter, set the pan over low heat whisking constantly until the butter is melted. Cook until thickened, strain through a sieve, cool to room temperature and keep in the fridge until ready to use.
Dissolve the cornstarch in 50ml whole milk, leave to rest.
In a small saucepan over medium heat combine the heavy cream, the leftover milk, 75gr sugar, pinch salt, bring to an almost boil, add 100gr either Marshmallow Fluff or plain marshmallows big or small, take the saucepan off the heat and leave until the marshmallows are completely melted. Then return the saucepan to the medium high, bring to an almost boil once again, add the cornstarch milk and cook constantly stirring until thickened. Take off heat, 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 crumbs at the last couple of minutes of churning. Keep in the freezer until set.