Combine water and salt in medium stove top pan over high heat. Once water is boiling, lower heat and add in oats. Simmer, stirring occasionally for 10 minutes.
After 5 minutes, whisk in vanilla extract, unsweetened applesauce, 2/3rds of the chopped apples, ground cinnamon, and maple syrup.
Continue to cook 5 minutes until a majority of the water is absorbed. Remove from heat and let cool 5 minutes. When ready to eat, pour into a bowl.
Top with chopped walnuts and the remaining 1/3rd of the apple, or other desired garnish. Save leftovers in airtight containers for up to 5 days in the refrigerator or freeze for up to 3 months.