01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper, leaving overhang on two sides for easy removal.
02 - In a large bowl, combine oats, almond flour, coconut sugar, salt, and baking powder. Pour in melted coconut oil and vanilla extract, stirring until the mixture becomes crumbly and evenly moistened.
03 - Set aside 3/4 cup of the crumble mixture for the topping. Transfer the remaining mixture to the prepared pan and press it firmly into an even layer across the bottom to form the crust.
04 - Bake the crust for 10 minutes until lightly set. Remove from the oven and allow to cool slightly while preparing the filling layers.
05 - While the crust bakes, combine the soaked cashews, maple syrup, coconut cream, lemon juice, lemon zest, vanilla extract, and a pinch of salt in a high-speed blender. Blend until completely smooth and silky, scraping down the sides as needed.
06 - Pour the cashew cream over the partially baked crust and spread it into an even, smooth layer using a spatula.
07 - In a mixing bowl, gently toss the blueberries with lemon zest, lemon juice, maple syrup, and arrowroot starch until the berries are evenly coated.
08 - Scatter the blueberry mixture evenly over the cashew cream layer. Sprinkle the reserved crumble mixture across the top, allowing some blueberries to peek through.
09 - Bake for 30 minutes, or until the crumble topping is golden brown and the blueberry filling is bubbling at the edges of the pan.
10 - Let the pan cool completely at room temperature, then refrigerate for at least 2 hours to allow the layers to set firmly. Slice into 16 even squares using a sharp knife.