How to Make It
In a heavy, lidded pot, salt the water and bring it to a boil. Then pour the grits in a slow, steady stream, whisking as you go. Take as much time as you need to do this.
Reduce the heat to a simmer, whisking constantly until the mixture starts to thicken. When it starts to feel like the grits have absorbed the water and started to soften, you can place the lid on the pot for 5 minutes at a time, then return and stir out any lumps, taking care to check the bottom of the pot to make sure the grits aren't sticking. Repeat this as often as necessary until the mixture is thickened, sampling spoonfuls (carefully!) to make that individual grains are soft and not, well, gritty.
Remove from the heat, stir in butter, then cheese until fully incorporated and season to taste.