For the cognac raisins boil together 2tbsp water, the cognac and 3tbsp sugar, pour the hot syrup over the chopped golden raisins, let cool to room temperature then transfer into 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, the cocoa powder and the malted milk powder, cook until fully dissolved. Take off heat, add the chopped milk chocolate, let it melt then return to medium high heat, stir until fully dissolved. Bring the mixture to an almost boil, add the cornstarch milk and cook constantly stirring until thickened. Take off heat, add the cream cheese, stir until smooth and glossy. Cool to room temperature, then transfer to the fridge overnight.
Freeze in your ice cream maker according to the manufacturer's instructions adding the drained cognac raisins and biscoff cookie crumbs at the last couple of minutes of churning. Store in an airtight container or spoon right away.