Preheat oven to 325F
Grease an 8 or 9 inch baking dish with butter
In a medium bowl, combine oats, brown sugar, 1/2 cup nuts, raisins, craisins, orange zest, baking powder, cinnamon, and salt. Mix well
In another bowl, break up the eggs with a whisk then add in milk and vanilla until well combined
Add milk mixture to oats mixture, along with the melted butter
Scatter apples and bananas evenly along the bottom of the prepared baking dish. Pour the oatmeal mixture over top and spread evenly. Sprinkle with remaining 1/2 cup nuts
Bake 40-45 minutes until top is golden and oats are set