To make oatmeal in a slow cooker, pour 2 cups of oatmeal and 6 cups of water into the bottom of your slow cooker. Add about 1/2 cup of brown sugar, honey or agave nectar and 1 to 2 tablespoons of maple syrup to the mixture. Stir until well-combined.
Cook the oatmeal over low heat for eight hours. Then, add 1 1/2 cups whole milk or full-fat coconut milk and a pinch of salt to the mixture. Cook for an additional two hours. Scoop into bowls, and top with cinnamon, brown sugar or raisins before serving. Alternately, top each bowl with 1/4 cup of candied walnuts or almonds.