Put the porridge oats in a pan, titanium cup or billy can and add the water. Do not add salt or sugar like you would with traditional porridge. I like to add a small knob of butter.
½ cup porridge oats, 1 cup water, 1 tsp butter
Bring to the boil then simmer for 5-10 mins until creamy.If cooking on a Trangia, use the simmer ring to turn down the heat.If on a campfire, raise your billy can further from the heat so it doesn't dry out, burn or stick to your pan.
½ tsp marmite
Add the Marmite to the porridge in small increments, to suit your taste, and stir through. Half a teaspoon of Marmite should be enough to start with. Adding too much will leave you with a very salty, inedible breakfast.
Once the porridge is at the consistency you prefer, enjoy straight out of the pan/cup.If you want to be extra filthy, add some maple syrup for a very simple but indulgent yeasty/salty/sweet/creamy breakfast.
maple syrup
Video
Notes
To make measuring the ingredients easier when camping, you can use a cup to measure the oats and water. Use roughly twice as much water as oats.