Step 1

Coat the bottom and sides of a 4- to 6-quart slow cooker with cooking spray, olive oil, or coconut oil.

Step 2

Melt 1 tablespoon of the butter over medium-high heat in a large saucepan or Dutch oven. Add the oats and stir frequently until lightly toasted, about 3 minutes. Push the oats up to the side of the pan and melt the remaining tablespoon of butter in the center of the pan. Add the pumpkin purée to the center of the pan and cook without stirring for 1 minute. Add the ginger, nutmeg, and cloves into the purée and cook, stirring occasionally, until the purée darkens slightly and the raw smell disappears, 3 to 4 minutes more.

Step 3

Transfer the mixture to the prepared slow cooker. Add the water, milk, maple syrup, cinnamon stick, vanilla, and salt and stir well to combine.

Step 4

Cover the slow cooker and cook on the LOW setting for 8 hours. When finished, much of the pumpkin purée will have separated from the oats — don't panic! Stir well with a wooden spoon to recombine everything, and remove the cinnamon stick before serving. Spoon the oatmeal into bowls and finish with a splash of heavy cream, a dusting of ground cinnamon, and a drizzle of maple syrup, if desired.