Preheat oven to 375 degrees. In a medium bowl, mix together the oats, baking powder, pumpkin pie spice, and salt.
In a large measuring cup, whisk together the almondmilk, pumpkin puree, honey, eggs, vanilla, and butter or coconut oil. Add liquid mixture to dry mixture in the bowl and stir to just combine. Add chopped nuts.
Grease an 8x8 or 9x9 baking dish with butter or spray with cooking spray. Pour oat mixture into pan and bake for 25-30 minutes or until the oats have absorbed the liquid and the baked oatmeal is set.
Let cool for 10 minutes in pan and serve, or refrigerate in a storage container for up to 5 days. Reheat in microwave before serving.