Combine. Combine oats, milk, water, salt, and brown sugar in a medium pot. Stir well before heating.
1/2 cup rolled oats, 1/2 cup milk of choice, 1/2 cup water, 1/8 tsp salt, 3 tsp brown sugar
Cook. Heat over medium, bring to gentle boil, then reduce heat and cook until creamy but easily stirrable (about 5–10 minutes), stirring often.
Add pumpkin. Stir in pumpkin puree, cinnamon, and nutmeg, and cook for another 1–3 minutes until thick to your liking.
3 tbsp pumpkin puree, 1/2 tsp cinnamon, Pinch nutmeg
Taste. Remove from heat, taste, and adjust sweetness or spices if desired.
Serve. Serve in a bowl topped with Greek yogurt and apple slices. Enjoy warm.