Start with the syrup, by mixing the ingredients for it and putting it on high heat to boil. Once boiling, lower the stove to low and let cook for 8-10 min.
Now it's time to make the cream mixture. Heat the greater portion of the milk with the sugar. In the rest of the milk, dissolve the pudding packets. Pour the dissolved puddings in a thin trickle to the heated milk on low heat, while stirring nonstop until thickened.
Cover with plastic wrap and put in the fridge to cool completely.
Beat the liquid cream to foam with a mixer. Add the cooled pudding to it in lots while stirring with the mixer nonstop to a fluffy, homogeneous cream.
For the layer, beat the eggs and sugar to a fluffy cream with a mixer. Add the oil in a thin trickle and the other dry ingredients, mixed together ahead of time, while stirring with a spatula.
Smear a rectangular or square tray with butter and distribute the mixture evenly in it.
Bake in a preheated 356°F (180 °C) oven for about 30 min.
Pour the cold syrup evenly over the baked and hot cake, cover with aluminum foil and leave it to cool completely.
Spread the cream mixture over the cooled cake and sprinkle with the ground walnuts. It's best to leave it for 2 hours at least, prior to serving. If you can resist the aroma and its temptation that is.