Preheat oven to 350 degrees. Grease an 8x8 baking dish or round pie plate and set aside.In a large bowl, combine the oats, sugar, baking powder, salt, cinnamon, and pumpkin pie spice.In a separate smaller bowl, mix together the pumpkin puree, banana, milk, vanilla, eggs, and butter.Stir the wet mix into the dry mix. Fold in the nuts. Pour mixture into prepared baking dish and spread evenly.Bake for 35-40 minutes until edges are golden brown, or a toothpick inserted in the center comes out clean.