Preheat oven to 375 and line a square baking dish with parchment paper. Leave extra on the sides so you an use it to pull the bars out.

In a medium bowl, combine oats, flour, baking soda, salt, cinnamon and light brown sugar. Mix until fully combined.

Add in melted butter and vanilla extract. Mix until a loose, dry(ish) crumble forms.

Pour half of the oat mixture into the bottom of the pan and press down firmly creating the base of the bars. Save the other half of the crumble and set aside.

In a small bowl, combine blueberries, sugar and cornstarch. Mix until blueberries are fully coated.

Pour coated blueberries on top of oat base layer.

Sprinkle the remaining oat mixture on top of blueberries.

Bake for 45 minutes at 375 or until blueberries are bubbly and starting to burst.

Let cool completely before cutting into bars or squares. Store in fridge!