Preheat the oven to 350°F. Spray a muffin tin with cooking spray, set aside.
In a large bowl whisk the eggs, milk, pumpkin puree, oil, and vanilla until smooth.
Add the oats, brown sugar, baking powder, salt, cinnamon, and pumpkin pie spice. Whisk until smooth and evenly combined.
Use a large cookie scoop to portion out the batter into the 12 muffin tins.
Sprinkle the chocolate chips or pecans overtop (can top with whatever you'd like!)
Bake for 20 minutes. Remove from the oven and allow to cool in the muffin tin for 5 minutes. Transfer to a wire rack to cool slightly. Serve warm, at room temperature, or cold.
Store the oatmeal cups in an airtight container in the fridge.