These Pumpkin Muffins are incredibly light, fluffy, and moist. For added decadence, I top them with a simple streusel. Traditionally streusels tend to be butter heavy, but this one is light and simple—with only three ingredients: brown sugar, walnuts, and cinnamon.
Preheat oven to 350°F (175°C) with a rack in the center position. Line a standard 12-cup muffin pan with liners or lightly grease with baking spray. Set aside.
In medium bowl, whisk together the all-purpose flour, whole wheat flour, ground cinnamon, baking soda, baking powder, salt, ground ginger, and ground cloves. Set aside.
In a small bowl, mix together the walnut streusel ingredients. Set aside.
In a small measuring cup, whisk together the milk and vanilla extract. Using a hand-held mixer or stand mixer fitted with a paddle attachment, beat the butter until creamy, about 30 seconds. Turn up mixer to high speed and slowly add granulated sugar. Beat until light in color, about 3 to 4 minutes. Beat in eggs one at a time.
Turn mixer to low speed and add in pumpkin puree until just blended. Add flour mixture in three additions, alternating with two additions of milk/vanilla mixture. Beat at low speed until just combined.
Using spoon, divide batter evenly among the muffin pan. Using hand or spoon, distribute and sprinkle the walnut streusel topping onto the batter. Lightly pat down with fingers.
Bake for 22 to 25 minutes or until toothpick inserted comes out clean. Set muffin tin on cooling rack and let sit for 5 minutes. Remove muffins from pan, place on cooling rack, and allow to come to room temperature before serving.