Combine the digestive biscuits or graham crackers, dark chocolate, coconut oil or almond/cashew butter, maple syrup, and a pinch of salt in a blender or food processor. Blend until the mixture becomes a coarse crumble that almost sticks together. I like to pulse the mixture so some small chunks of chocolate remain for extra texture.

Divide the cookie crumble mixture from Step 1 evenly among four jars, pressing it down gently to form a solid base layer. Try to distribute it evenly so each jar gets a tasty, crunchy foundation.

In a mixing bowl, combine the raspberry oat dessert and diced fresh strawberries. To enhance the pink color and integrate the flavors, gently crush a few pieces of the strawberries while mixing. Stir until the mixture is well combined and slightly chunky.

Spoon the berry oat dessert mixture from Step 3 over the cookie crumble base in each jar, dividing evenly. Smooth the tops for a neat layer. If you want even more berry flavor, you can add a few extra crushed strawberries to the very center of each jar.

Pour the oat cream for whipping into a mixing bowl. Add the vanilla sugar or vanilla bean powder. Whip using an electric mixer or whisk until the cream is fluffy and holds soft peaks. For extra flavor, I sometimes add a tiny extra pinch of vanilla.

Pipe or spoon the fluffy vanilla oat cream from Step 5 on top of the berry layer in each jar. Serve the Neapolitan cake jars chilled, with a long spoon, so each bite has all three delicious layers together. Enjoy!