Preheat the oven to 375F and line a 9×13 baking dish with parchment paper. In a large mixing bowl, stir the oats, oat flour, salt, and cinnamon together.

Pour in the melted butter, egg, and vanilla and stir together until you have a damp, clumpy mixture. It will be crumbly, and not a dough. Reserve about a cup of the mix, then press the rest into the baking dish in an even layer.

Spread the thawed berries over the oat mixture and pour any juice over the top. sprinkle the rest of the oats over the berries and bake for 25-30 minutes. Allow the bars to cool completely before cutting. Cut the bars into 12 squares and store them in an airtight container in the refrigerator for up to a week.