Prepare the crust and crumble mixture by combining almond flour, coconut flour, melted butter, sweetener, vanilla, and water in a bowl. Mix until a crumbly dough forms. Press half of the mixture evenly into a lined baking pan to create the base, ensuring it is compact and smooth.

Bake the crust in a preheated oven at 350°F (175°C) for about 10–12 minutes until the edges turn lightly golden. Remove from the oven and allow it to cool slightly while you prepare the filling.

In a saucepan over medium heat, combine raspberries, lemon juice, sweetener, and water. Cook until the berries break down and the mixture thickens into a jam-like consistency. Lightly mash some berries while keeping a few chunks for texture.

Spread the raspberry filling evenly over the baked crust. Sprinkle the remaining crumble mixture on top. Return to the oven and bake for 15–20 minutes until the top is golden and slightly crisp. Cool completely before slicing into bars.