Add the butter to the Instant Pot® and press the ‘saute’ button. Once the butter has melted, add the oats and stir to incorporate. Toast the oats for 5 minutes, stirring occasionally.
Add the water, milk and salt to the pot and close the Instant Pot®. Put the steamer Valve on ‘seal’ and then press the ‘Manual’ button. Set the timer for 5 minutes on high pressure. When the cooking cycle is complete, open the steamer valve and release the pressure.
Open the lid and stir the raisins, cinnamon and brown sugar into the mix.
In a separate bowl, mix together the powdered sugar and remaining milk. Drizzle this icing over the oatmeal in the bowl and enjoy warm.