1 serving cooking spray (optional)
1 cup buttermilk
1/3 cup honey
1/2 banana, mashed
1/4 cup canola oil
2 tablespoons egg white
1 teaspoon vanilla extract
2 1/2 cups whole wheat flour
1 tablespoon baking powder
1 tablespoon flax seeds, or more to taste
1/2 teaspoon baking soda
1/2 teaspoon ground cinnamon, or more to taste
1/4 teaspoon salt
18 dates, pitted and chopped, or more taste
1/2 cup chopped walnuts
Preheat oven to 375 degrees F (190 degrees C). Grease muffin tin with cooking spray or line with paper liners.
Beat buttermilk, honey, mashed banana, canola oil, egg, egg white, and vanilla extract together in a bowl.
Combine whole-wheat flour, baking powder, flax seeds, baking soda, cinnamon, and salt in a large bowl. Mix in dates and walnuts. Pour in buttermilk mixture; mix the batter until blended.
Scoop batter into the prepared muffin tin.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, 20 to 25 minutes. Transfer to a wire rack to cool, about 15 minutes.