01 - Preheat the oven to 350°F. Line an 8x8-inch baking pan with parchment paper, leaving an overhang on two sides for easy removal.
02 - In a large bowl, combine the rolled oats, flour, brown sugar, baking powder, and salt. Pour in the melted butter and vanilla extract, stirring until a crumbly dough forms. Firmly press two-thirds of the mixture into the bottom of the prepared pan to create an even, compact base layer. Set aside the remaining crumble for the topping.
03 - Combine the diced strawberries, granulated sugar, and lemon juice in a saucepan over medium heat. Cook, stirring frequently, until the berries soften and release their juices, about 5 minutes. Sprinkle in the cornstarch and continue cooking for 1 to 2 minutes until the mixture thickens. Remove from heat and let cool slightly.
04 - Add the soaked and drained cashews, coconut cream, maple syrup, lemon juice, melted coconut oil, vanilla extract, and a pinch of salt to a high-speed blender. Blend until silky smooth, scraping down the sides as needed, about 1 to 2 minutes.
05 - Spread the vanilla cashew cream evenly over the pressed oat crumble base. Spoon the slightly cooled strawberry compote over the cream layer, then lightly swirl with a knife for a marbled effect. Sprinkle the remaining crumble mixture evenly across the top.
06 - Bake for 30 to 35 minutes until the top is golden brown and the filling is set. Cool completely in the pan, then refrigerate for at least 1 hour before slicing.
07 - Lift the slab out of the pan using the parchment overhang. Cut into 12 even bars and serve chilled or at room temperature.