Preheat your oven to 350°F (175°C) and line an 8x8-inch baking pan with parchment paper or lightly grease it.
In a large bowl, mix the applesauce, milk, honey/maple syrup (if using), egg, oil/butter, and vanilla extract. Mix well!
In the same bowl, add in the oat flour, baking powder, cinnamon, and salt. Mix until just combined. The batter should be thick but still spreadable, if too thick you can add 1-2 tbsp milk of choice until a better consistency.
Pour the batter into the prepared baking pan and spread it evenly. Bake for 18-22 minutes, or until a toothpick inserted into the center comes out clean.
Allow the bars to cool completely in the pan before cutting into squares.