Preheat the oven to 350 F. Spray a 9x9 baking dish with cooking oil and set aside.
In a large mixing bowl, combine all ingredients except for the oats and baking powder. Whisk together until the pumpkin mixture is smooth, and everything is well incorporated.
Add the oats to the bowl and sprinkle over the baking powder. Stir with a rubber spatula until the baking powder is evenly distributed and the oats are fully coated in the pumpkin mixture.
Transfer the oats to the prepared baking dish and place in the preheated oven for 35-45 minutes (40 minutes was perfect for my oven). There can be a little softness to the center of the oats because it will continue to set while cooling, but it shouldn’t be goey or jiggle. Remove from the oven and allow it to cool for 15 minutes before serving.