Preheat the oven to 375°F. Lightly grease an 8x8 baking dish.
In a large bowl, combine the rolled oats, baking powder, and salt. Stir until evenly mixed.
Add the pumpkin puree, pumpkin spice extract, milk, eggs, vanilla extract, and maple syrup. Stir until everything is well combined and the oats are fully coated.
In a medium bowl, mix together the melted butter, flour, brown sugar, and cinnamon until it forms a crumbly texture.
Pour the oatmeal mixture into the prepared baking dish and spread evenly. Sprinkle the cinnamon crumb topping over the top.
Bake for 30–35 minutes, or until the center is set and the topping is lightly golden.
Let cool slightly before slicing.