What is oatmeal with brown sugar and raisins typically cooked in?

Oatmeal is typically cooked in water, which is the primary liquid used to rehydrate the oats and help them swell as they absorb the liquid during cooking. This process results in a creamy texture that is characteristic of oatmeal. When cooked in water, the oats come together to form a soft and palatable dish, allowing for various toppings, such as brown sugar and raisins, to enhance the flavor.

While milk can also be used to add creaminess and a richer flavor to oatmeal, the standard preparation often starts with water. Broth and butter are not common liquids for cooking oatmeal, as broth would impart an unexpected savory flavor, and butter is usually added after cooking for richness rather than as a cooking medium.