Skinny Pumpkin Spice Muffins with Walnut Streusel

Preheat the oven to 350 degrees F (175 degrees C). Grease two 12-cup muffin tins.

Sift together whole wheat flour, all-purpose flour, baking powder, pumpkin pie spice, cinnamon, and salt in a large bowl.

Combine pumpkin puree, egg whites, and egg in a large bowl; beat with an electric mixer until combined. Mix in white sugar, brown sugar, olive oil, and vanilla extract. Slowly add flour mixture to the pumpkin mixture, stirring until just combined. Fill the prepared muffin cups a little more than 1/2 full with batter.

Combine brown sugar, diced butter, oats, walnuts, and flour for the streusel in a small bowl. Use a fork or your hands to combine until mixture resembles rough crumbs. Divide crumbs evenly amongst the muffin cups.

Bake in the preheated oven until tops spring back when lightly pressed, about 20 minutes.