Preheat oven to 350 degrees F (175 degrees C). Grease a rimmed baking sheet.
Place apples wedges in a bowl. Sprinkle brown sugar and 1 teaspoon cinnamon over the apples and toss. Add 1/2 cup flour and mix well. Place apple mixture on the prepared baking sheet.
Place the remaining 1/2 cup flour in another bowl. Cut in butter with 2 knives or a pastry blender until it's the size of small peas. Add the remaining 1 teaspoon cinnamon, oats, walnuts, maple syrup, pumpkin pie spice, vanilla extract, and salt. Spoon mixture over the apples.
Bake in the preheated oven until fruit mixture is bubbling, 45 to 50 minutes.