1. Crumble the biscuits into fine crumbs using a blender or put them in a plastic bag and use a rolling pin or glass to crush them.
2. Melt the butter and mix it well with the biscuits, then transfer to a 9″ (23 cm) form, with a releasable bottom if possible (if you don't have one of this size, you can use a slightly smaller or larger one). If you'd like to make it easier to take the cake out, put aluminum foil along the bottom and walls of the form.
Press the biscuit mixture with the underside of the spoon, so it sticks well and forms a thick base layer. Cover with plastic wrap and leave it in the fridge to harden while you're making the cake mixture.
3. Pour the milk, sugar, mastika, lemon rinds, vanilla and cinnamon (powdered or sticks, 2 are enough) in a pot. Once the milk comes to a boil, add the washed rice (but not too thoroughly, to avoid washing away all the starch). Lower the heat and boil about 30 min. or until you see that it's very swollen.
4. Remove from the heat, take out the lemon rinds and cinnamon sticks, if you've used such. Let cool a little but do not let it get cold. If too much of the milk has been absorbed, you can add a little more - the mixture needs to be a bit runnier than in the classic milk with rice recipe.
5. Blend to a mixture that's as smooth as possible. You may see tiny pieces of rice and that's ok, it still turns out beautiful. Finally, add the gelatin that you've hydrated beforehand as directed on the packet. This needs to happen while the mixture is still practically hot, so you have to work fast.
6. Pour the milk-rice mixture over the biscuit layer and let it cool completely, then wrap it with plastic wrap and put in the fridge for at least 4 hours, to harden.
7. Decorate the cake by sprinkling on cinnamon or powdered cocoa, if you're not a big fan of cinnamon.
8. Always serve it well chilled.
I hope you like this unusual little recipe!