Dissolve the cornstarch in 50ml whole milk, leave to rest.
For the white chocolate base in a small saucepan combine the leftover milk, heavy cream, sugar and a pinch salt, stir to combine, put on medium heat, cook until almost boiling. Take off heat, add 100gr chopped white chocolate, let the chocolate dissolve then stir until completely smooth. Return to medium heat, add the cornstarch milk and cook constantly stirring until thickened. Take off heat, add the cream cheese, cool to room temperature, then transfer into the fridge overnight.
For the caramelised white chocolate stracciatella preheat the oven to 130C. Spread 75gr chopped white chocolate on a baking pan, add the cocoa butter, place in the oven and bake 10min, then take out, stir with a spatula to reveal a slightly more caramelised layer of chocolate underneath. Return to the oven and bake another 10min, then remove and stir again. Continue thus caramelising and stirring the chocolate until it turns a lovely golden brown color reminiscent of dulce de leche.
Freeze the ice cream base in your ice cream maker according to the manufacturer's instructions pouring in a thin stream of hot caramelised white chocolate at the last couple of minutes of churning. Wait for the chocolate stracciatella to seize up, then transfer into an airtight container for storage. Keep in the freezer or spoon right away.