01 -
Preheat the oven to 375°F (190°C). Line an 8-inch square baking pan with parchment paper, leaving some overhang on the sides for easy removal later.
02 -
In a large bowl, mix together oats, flour, brown sugar, baking soda, salt, and cinnamon (if using). Stir in melted butter and vanilla extract until the mixture is crumbly.
03 -
Press half of the oat mixture firmly into the bottom of the prepared pan to form a solid base.
04 -
In a separate bowl, toss blueberries with granulated sugar and cornstarch until evenly coated. Spread this blueberry mixture evenly over the oat base.
05 -
Crumble the remaining oat mixture over the blueberries, gently pressing down to create a topping layer.
06 -
Bake for 35-40 minutes, or until the top is golden brown and the blueberries are bubbly around the edges.
07 -
Allow the bars to cool completely in the pan on a wire rack. Once cooled, use the parchment paper overhang to lift the bars out of the pan and cut into 12 squares.