Preheat oven to 180°C / 356°F.
Add walnuts, almonds, cinnamon, nutmeg, cloves, in a blender and blend until nuts look finely chopped. Transfer to a bowl and mix together with the sugar.
Remove filo from its package and lay it open on your working surface.
With a pastry brush, grease a 32x25 baking dish or pan with melted butter. Brush both the bottom as well as the sides of the pan.
Take one filo sheet and place it in the pan so half of the filo covers the bottom of the pan and the other half of it hangs out of the pan. Brush with butter here and there. Add 3 more filo sheets the same way (creating a cross) to cover the walls of the pan all around and brush each one with butter as well.
Then with a sharp knife cut the remaining filo stack in half. Now each filo sheet is going to fit in the pan. Cover the stack with a tea towel so it won't air-dry.
Sprinkle the filo in the pan with 6 tablespoons of the sugar and ground nuts mixture.
Take another filo sheet from the stack and add it to the pan. If it's slightly bigger simply fold one edge inwards to fit. Brush with butter.
Add another filo sheet the same way and brush it with butter.
Sprinkle 6 tablespoons of the nut and sugar mixture on top.
Then add half of the rice pudding filling. And spread it evenly all over.
Add 3 more filo sheets on top of the filling brushing each one with butter.
Again sprinkle 6 tablespoons of the sugar and nuts mix.
Then repeat adding: 3 more filo sheets, 6 tablespoons of sugar and nuts, and then add the remaining half of the rice pudding filling on top.
Add 3 more filo sheets, 6 tablespoons sugar and nuts, 3 filo sheets, and the last 6 tablespoons of the sugar and nuts.
There should be only 6 filo sheets left now. If they're less it's okay. Some packages have 1 filo sheet less or more.
At this point fold on top of the pie the filo that hangs out of the pan. Brushing it with butter well, so it sticks together nicely.
Now add the last filo sheets on top brushing each one with butter.
Cut and divide the pie into 12 square pieces. Cutting it all the way through to the bottom. Sprinkle (more like spraying) the top of the filo with a tiny bit of water.
Bake for 40 to 45 minutes. Until it gets deep golden on top. Shake the pan or baking dish to see if the pie moves in it. That means it's nicely baked at the bottom as well. Let it stand for 15 minutes before serving.