Preheat oven to 375 degrees.
Line a 9x9 pan with parchment & set aside.
In mixer bowl - combine cake mix, oats & melted butter - stir on low until fully combined & crumbly.
Press 3/4 of the mix into your prepared dish making a nice even bottom layer.
Add in your blueberry syrup spreading out to evenly coat.
Top with blueberries.
Sprinkle remaining mix over the top - pressing in slightly.
Bake 19-25 minutes or until golden brown.
Cool completely before cutting.
Dust with confectioners sugar if desired before serving.