Oat-Nut Topping
Preheat the oven to 350° F
Place the walnuts on a baking sheet and toast for 5-10 minutes, or until fragrant.
Allow to cool and chop into small (~ ¼ inch) pieces
Increase the oven temp to 400° F
In a medium bowl, add the rolled oats, flour, sugar, walnuts, and salt. Drizzle in the oil, stirring lightly with a wooden spoon
Drizzle in the water and toss. (The topping should be crumbly). Set aside
Mix the cinnamon and sugar in a small bowl.
Set aside
Filling
Peel and core the apples
Slice the apples into ¼" slices and cut each slice into thirds.
In a large bowl, toss all the filling ingredients together
Pour into an 8 x 8" baking dish (or the equivalent)
Assemble
Sprinkle the reserved oat-nut topping evenly over the apples, making sure they're completely covered.
Sprinkle the cinnamon-sugar over the top
Bake for 15 min at 400° F. then reduce the heat to 350° and bake an additional 15 to 20 minutes, or until the topping has cooked and a toothpick inserted into the apples indicates they're cooked through
(Note: If the topping is browned before the apples are completely tender, cover with a piece of aluminum foil to finish baking)
Remove the crisp from the oven and let it cool