Whip together heavy cream and sweetened condensed milk.Combine heavy cream and 1 tablespoon of the sweetened condensed milk in a tall container. Whip using a handheld milk frother until you get medium peaks. Set aside.
Blend milk, ice, instant coffee, chocolate syrup, and sweetened condensed milk.All mocha ingredients go into a blender. Use a tamper tool to make sure the ice gets blended evenly. Start on low for about 5-10 seconds then turn it up to high for about 3 seconds. It should be nice and slushy.
Pour frozen mocha into two cups.Each serving is 17 oz. -- a Starbucks grande is 16 oz.
Top with whipped cream and garnish with a little chocolate syrup.Spoon on the whipped cream and squeeze on a little chocolate syrup. Serve with a straw and drink immediately.