Preheat oven at 350°F (180°C). Line an 8x8-inch baking pan with parchment paper. Slightly oil the paper with coconut oil, set it aside.
In a mixing bowl, combine all the bottom and top crust ingredients: oat flour, rolled oat, salt, cinnamon, maple syrup, vanilla, and maple syrup. Stir to bring ingredients together and when it starts to be difficult to stir, squeeze the ingredients together by hands. The batter should be slightly dry and crumbly but hold together when squeezed.
Set aside 1/2 cup of the oat mixture in a bowl - you will use this for the top layer later in the recipe.
Spread the remaining oat mixture all over the prepared pan and press with a spatula firmly to pack the ingredients into an even layer with no hole.
Place the baking pan in the fridge.