Preheat your oven to 350°F (175°C) and line a standard 12-cup muffin tin with parchment liners or coat with cooking spray. This preparation ensures your muffins won’t stick.
Combine the dry ingredients in a large bowl: flour, oats, baking soda, salt, cinnamon, nutmeg, and ginger. Whisk together until well mixed and no clumps remain.
In a separate bowl, whisk together the wet ingredients: pumpkin puree, eggs, oil, both sugars, milk, and vanilla extract until smooth and well combined. The mixture should be thick but pourable.
Pour the wet ingredients into the dry ingredients and gently fold together using a spatula until just combined. Stop when you no longer see dry flour—overmixing will make your muffins tough.
Fold in the chocolate chips with just a few strokes, reserving a small handful for topping the muffins. This ensures even distribution while maintaining a tender crumb.
Divide the batter evenly among the prepared muffin cups, filling each about ¾ full. Sprinkle the reserved chocolate chips and optional oats on top of each muffin.
Bake for 22-25 minutes or until a toothpick inserted into the center of a muffin comes out clean or with just a few moist crumbs (not wet batter). The tops should spring back when lightly touched.
Allow the muffins to cool in the pan for 5 minutes before transferring to a wire rack to cool completely. This resting period helps the muffins set properly.