Prepare an ice water bath in a large bowl.
Create a slurry made with the 2 tablespoons of milk and cornstarch, whisk until smooth, set aside.
Whisk the cream cheese into the warm chocolate syrup until smooth.
In a heavy bottom 3.5 to 4 quart saucepan, combine the 1 ½ cups milk, cream, the remaining ½ cup sugar and corn syrup. Bring to a boil over medium-high heat, stirring frequently, and cook for 5 minutes. Off-heat whisk in the cornstarch slurry. Set the saucepan back on the heat and cook until slightly thickened, about 1 minute.
Combine the chocolate mixture with the cream mixture in a large glass or metal bowl and place in an ice water bath. Stir every 5 minutes until chilled, cover and refrigerate overnight or at least 8 hours. Process according to your ice cream maker directions.
Once the ice cream is frozen, layer ⅓ of the chocolate ice cream in an air-tight freezer safe container. Spoon ⅓ of the raspberry sauce on top and sprinkle with ⅓ of the chopped semi-sweet chocolate chunks, then repeat twice more with a layer of chocolate, then raspberry, then chocolate chunks, etc.
Freeze the ice cream at least 4 hours or overnight before serving.