Place Guinness and brown sugar in a saucepan and bring to a boil over high heat. Lower heat to medium-high and reduce the liquid by half. This will take about 20 minutes and you will end up with approximately 1/2 cup of syrup.
In a separate saucepan, bring the three cups of water to a boil and slowly stir in the oats and add the pinch of salt. Reduce to a simmer and cook for 25-30 minutes. This mixture will need to be stirred frequently to prevent burning on the bottom. This recipe will yield 2 generous portions of oatmeal or 4 smaller ones.
Once the liquid has sufficiently reduced, it will lightly coat the back of a spoon. The mixture may still appear a bit thin to you at this point, but
will continue to set up and thicken as it cools.
When oatmeal is cooked to your liking, place in a bowl and drizzle with the Guinness syrup.