Add the cashews to a bowl and cover with boiling water. Soak for 2 hours.
Place the biscuits in a zip bag and crush them with a wooden spoon after you closed the bag. You could also add them to a food processor and pulse several times (don't grind it too finely).
Juice the lemons. You need exactly 200 ml of fresh lemon juice.
Drain the cashews and add them to a high-speed blender (see notes) with the lemon juice, non-dairy cream, water and maple syrup. Blend until perfectly smooth (it can take 3 to 5 minutes).
Add the lemon cream to a saucepan with the agar-agar. Use a spoon to gently incorporate the agar. Heat the cream over medium to high heat until bubbles start to appear. Let it bubble for 1 minute over medium heat until it thickens. Use a whisk to stir the entire time.
Fill 4 glasses with cream to about one-third of their volume. Top with biscuit crumbs and more pudding. Let it cool for 30 minutes. Then, let them sit in the fridge for another 2 hours (or overnight) to set. Top it generously with more biscuit crumbs right before serving.