Alton Brown's Orange Caesar Recipe

Ingredients
8 1/2 ounces freshly squeezed orange juice, divided
1/2 orange, zest finely grated
1/2 cup whole milk
1 tablespoon powdered sugar
1/2 teaspoon vanilla extract
Directions
Pour 6 1/2 ounces of the orange juice into an ice cube tray and freeze until solid, approximately 2 hours. Store the remaining 2 ounces of juice and the zest in an airtight container in the refrigerator until ready to use.
In the carafe of a blender combine the frozen juice cubes, reserved orange juice and zest, milk, powdered sugar and vanilla, and blend until smooth and slushy, 30 to 45 seconds. Serve immediately.