Add chopped apples, cranberries, brown sugar, butter, cinnamon, ginger, nutmeg, salt, and 2 Tbsp water to a large saucepan over medium-high heat.
Once simmering, let cook for 3-5 minutes, stirring occasionally, until apples are tender and cranberries are just starting to burst. Remove 3 Tbsp mixture to separate bowl (you'll use this as a topping).
Add remaining 1 ¾ cups water to saucepan and let come to a simmer. Add oats and cook for about 5 minutes, stirring occasionally, until oats are cooked and mixture is creamy.
Serve in bowls and top with reserved apple/cranberry mixture.