Mix the cornstarch with 50ml whole milk, leave to rest.
In a small saucepan combine the leftover milk, sugar and a pinch salt, stir, place on medium heat, bring to an almost boil, add the cornstarch milk and cook constantly stirring until thickened. Take off heat and let cool a little.
In a blender combine the unsweetened chestnut purée and the warm ice cream base, blend in high until silky smooth and fully combined. Transfer to the fridge overnight.
Freeze in your ice cream maker according to the manufacturer's instructions adding the desired amount of crushed meringues (I used 3 handfuls) and at the last two minutes of churning. Store in an airtight container in the freezer.
Pair with dark chocolate and vanilla bean ice creams.