Heat a large skillet over medium heat. Add oats and coat with butter. Toss in the pan until lightly toasted, about 5 minutes.

While the oats are toasting, bring the water, milk, sugar, and salt to a simmer over medium heat in a large Dutch oven or saucepan

Add the oats and bring to a gentle boil, then reduce the heat to low, partially covering the pot.

Cook until thickened, about 25 to 30 minutes, stirring occasionally. The oats will still be a little loose, but will thicken as they stand.

Stir in the vanilla. Serve