Preheat your oven to 350°F (175°C) and line an 8x8 inch baking pan with parchment paper.

In a large mixing bowl, combine rolled oats, almond flour, maple syrup, melted coconut oil, vanilla extract, baking powder, and salt. Stir until well incorporated.

Reserve about 0.5 cups of the mixture for topping and press the rest into the bottom of the lined pan.

In another bowl, mix fresh or frozen berries, lemon juice, and cornstarch until berries are coated.

Spread the berry mixture evenly over the pressed oat crust.

Sprinkle the reserved oat crumble evenly on top of the berry layer.

Bake in the preheated oven for 30-35 minutes until golden brown.

Let the bars cool completely in the pan before lifting out and slicing.