01 -
Heat up your oven to 375°F. Grab a 20x20 cm square pan, line it with parchment paper, and leave a little extra hanging over the edges to make removing easier.
02 -
Toss the oats, flour, brown sugar, baking soda, salt, and cinnamon (if using) into a large bowl and stir it up.
03 -
Pour in the melted butter and vanilla. Stir until you get a crumbly mix.
04 -
Press half of the oat mixture firmly into the bottom of the prepped pan to form a solid layer.
05 -
Grab a different bowl and toss in the blueberries, powdered sugar, and cornstarch. Mix until everything’s evenly coated, then spread over the oat base.
06 -
Sprinkle the remaining oat crumble over the blueberries, gently pressing it down without squishing the berries.
07 -
Pop it in the oven for 35-40 minutes, or until the top looks golden and the blueberries are bubbling a little.
08 -
Set the pan on a cooling rack and let everything cool completely. Once cool, lift out the squares using the parchment paper and cut them up into pieces.