Preheat oven to 350 degrees. Spray 8x8 baking pan with nonstick spray and set aside.
Add milk, mashed banana, honey, olive oil, egg, and vanilla to a large bowl then whisk to combine.
Add 1.5 cups of barley flakes, barley flour, cinnamon, baking powder, and salt, then stir to combine.
Fold in chopped pecans, then pour batter into prepared baking pan.
Bake for 30-35 minutes, or until edges are golden brown and an inserted toothpick comes out clean. Let cool before slicing into bars. Store in refrigerator or individually wrapped in the freezer.