Strain the milk mixture through a sieve lined with a layer or cheesecloth. (Or do as I did and strain it through a paint straining bag, which I also use to make nut milks. They're only a couple of dollars at hardware stores.)
Combine the remaining milk, cream, sugar and agave nectar in a 4-quart saucepan. Bring the mixture to a slow boil over medium heat and boil for four minutes. Remove from heat, add coffee grounds and let it seep for 5 minutes.
Fill a large bowl with ice and water.
In a medium bowl, whisk the cream cheese and salt until very smooth.
In a small bowl, mix about 2 tablespoons of the milk with the corn starch to make a smooth slurry.