Generously coat the inside of a 6-quart or larger slow cooker with nonstick cooking spray. Add the steel-cut oats and water. Stir to combine.
1 cup regular steel-cut oats, 3 1/2 cups water
Wash and dry the pumpkin. Cut an opening around the stem large enough to reach inside with a spoon. Remove the top, seeds and stringy pulp. Leave the pumpkin skin intact. Do not pierce the pumpkin or replace its top.
1 small pie or sugar pumpkin
Place the hollow pumpkin upright in the center of the slow cooker, directly in the oat-and-water mixture. Make sure the pumpkin fits completely inside with the slow cooker lid fully closed.
In a small bowl, combine the brown sugar, cinnamon, nutmeg and optional cloves. Spoon the mixture inside the pumpkin, then place the butter pieces over the top.
1/3 cup brown sugar, 1 tsp ground cinnamon, 1/4 tsp ground nutmeg, pinch cloves, 2 Tbsp salted butter
Cover the slow cooker and cook on low for approximately 7 hours, until the oats are tender and the pumpkin flesh is very soft and easy to scoop. If the flesh is still firm, replace the lid and cook for another 15–30 minutes, then check again.
Remove the lid. The oats may appear dry before the pumpkin is incorporated, so wait to add more liquid. Leaving the pumpkin in the slow cooker, carefully scoop the softened flesh from its interior sides into the surrounding oatmeal. Add as much or as little flesh as desired, taking care to leave the outer peel behind.
Carefully spoon all the buttery, spiced liquid from inside the pumpkin into the oatmeal.
Wearing oven mitts, carefully lift the remaining pumpkin shell out of the slow cooker. The shell will be very soft and may tear or lose its bottom. Remove any pieces of peel from the oatmeal, leaving the pumpkin flesh and juices in the pot.
Add the vanilla extract. Use a potato masher to mash the pumpkin into the oats, leaving small, soft pieces if desired. Stir until evenly combined.
1 tsp vanilla extract
Let the oatmeal sit for 5–10 minutes, then stir again. Add a splash of milk, cream or water if needed to reach your preferred consistency. Serve warm with your favorite toppings.
Milk or cream, maple syrup, chopped pecans, brown sugar, ground cinnamon, granola