Place the uncooked rice in a blender or food processor and process for 3 to 5 minutes, till powdered.
Bring water to a simmer in a saucepan. Add rice powder turn heat down to low. Cook for 5 minutes, stirring constantly.
Remove from heat. Let cool slightly. Add breast milk, formula or more water to thin the rice to your desired consistency.
Serve slightly warm or at room temperature. You can store leftovers in the fridge for 2 days. To freeze for later: fill an ice cube tray with the cereal. Freeze for at least 2 hours, till solid. Remove cubes from tray and place in a freezer bag. To defrost, place in microwave for 30 seconds, or as needed.