Preheat oven to 350°F. Grease a 12-cup muffin tin with cooking spray and set aside.
In a medium bowl, whisk together the all-purpose flour, whole wheat flour, baking powder, baking soda, cinnamon, ginger, nutmeg, and salt. Set aside.
In a large bowl, beat together the egg and brown sugar until light and fluffy. Add in the oil, pumpkin puree, and vanilla extract and mix until combined.
Add the dry ingredients to the wet ingredients and mix until just combined.
In a small bowl, combine the chopped walnuts, oats, brown sugar, and flour. Add the melted butter and mix until the mixture is crumbly.
Divide the muffin batter evenly among the prepared muffin cups. Sprinkle the walnut streusel on top of each muffin. Bake for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool for 5 minutes in the pan before transferring to a wire rack to cool completely.
Interesting Facts
Pumpkin spice muffins are a great way to get in some extra vegetables while still enjoying a delicious treat.
Pumpkin is high in fiber, vitamin A, and potassium, making them a great snack for a healthy lifestyle.
Walnuts are a great source of omega-3 fatty acids, a type of healthy fat that can help reduce inflammation.