Place apples in a 23x33cm (9x13 in) baking dish. In a bowl, cream together butter and sugar. Stir in flour, oats and salt. Fold in nuts. Sprinkle oat mixture evenly over apples. Drizzle with maple syrup.
Bake in preheated oven 50 to 70 minutes, until apples are tender and topping is golden.