Whisk together 3/4 cup granulated sugar and 1/4 cup cornstarch in a large saucepan. Gradually whisk in 4 cups half and half cream until smooth. Heat the mixture over medium heat until it thickens to a pudding-like consistency, and it just starts to bubble, 10-15 minutes, reducing the mixture if needed if you feel like anything is starting to stick to the bottom of the pot.
Pour into a heatproof bowl or container (preferably one that is also freezer-safe and has a secure lid). Whisk in 2 Tablespoons rose water, and 1/2 teaspoon vanilla extract. Cover the mixture and place in the fridge to cool completely.
Once the mixture has chilled, freeze it using an ice cream maker of your choice, following the manufacturer's directions.
Ninja Creami Directions:
Complete step 1 of the recipe above as written. Once the mixture is done cooking, split the ice cream mixture into 2 pint-sized Ninja Creami containers. Cover the containers, and place them on a flat surface in the freezer to freeze completely (at least 24 hours). Place one of the containers in the Creami machine, and turn on the "Light Ice Cream" setting. Don't leave the machine unattended while it is blending. Add a re-spin if the ice cream looks "powdery" on the top after the initial blend (it probably won't). Divide into 2-4 bowls, and serve.