Line a 9x13 inch pan with parchment paper and set aside. You could also use a square pan, or even a big Tupperware.
In a small bowl, combine the instant coffee and water. Set aside. In a bowl, beat the heavy cream until stiff peaks form.
In a separate bowl, fold together the sweetened condensed milk, vanilla extract and coffee mixture. Pour the sweetened condensed milk mixture into the whipped cream and fold them together. Fold in the crushed Oreos.
Pour the ice cream into the prepared pan, top with remaining crushed Oreos, and freeze overnight or for at least 10-12 hours.