In a large bowl, toss sliced apples with cinnamon and salt. Mix in the vanilla, maple syrup, melted butter, and rolled oats. Apples should be uniformly coated.
Fold in the walnuts, then spread into a greased 8x8-inch baking dish.
Bake for 25 minutes. Then turn off oven and let the apples carry over cook for another 10.
Remove and serve warm with desired toppings.
Store in an airtight container in the fridge and serve within 5 days for best quality. Reheat before serving.
When popping in the oven, place on the center rack to make sure the apples and oats cook through evenly.
If you don't have an 8x8 inch baking dish, a 9x9 inch square or round cake pan will work.
If you have a large, 9x13 inch baking dish, it can be used, but the cooking time will be shorter. Check after baking for 15 minutes, looking for the apples and oats to be lightly browned, with 10 minutes carry over!
Apples: Swap the apples for what you have on hand. If using Granny Smith, they have a more tart flavor, so adjust sweetener accordingly (check out the FAQ for more info on apples!)
Chopped walnuts: You can purchase pre-chopped walnuts to make it a little easier on yourself, but if you've got whole walnuts, instead of chopping with a knife (which can lead to walnut pieces all over your kitchen), you can break them apart by hand. Alternatively, place 2-4 Tbsp at a time in a strong resealable baggie, and roll a rolling pin over top to break into pieces!
If you have a nut allergy in the house, feel free to omit and use seeds of choice. Pumpkin and sunflower are excellent additions!
If you're not a walnut fan, pecans are a great sub!
Rolled oats: You can sub quick/instant oats if you have them on hand or like your oats less chewy. No steel cut oats here though, they'll be too hard!
Plant based butter: I've used non-dairy butter here to keep this recipe vegan and it's what I keep in my kitchen. Use whatever butter your family keeps!
Added sugar: If you want to make this added sugar free, you can swap in date syrup or omit the syrup all together. However, I don't recommend no sweetener! I actually used a monk fruit maple syrup to keep it more diabetic friendly for my grandpa!