The most delicious custard cake

Pour water into a saucepan with a thick bottom, add a pinch of salt. As soon as it boils, we put oil. Turn down the heat and add flour, stirring constantly. We try not to form lumps. Remove from the stove and cool for about three minutes. After driving in one egg at a time, whipping the mass with a mixer so that the eggs do not boil. We will get a beautiful, elastic dough. Heat the oven to 180 degrees. We fill a pastry bag with dough and squeeze out long "sausages" on a baking sheet covered with parchment. These "sausages" will be the basis of our cake, so we make them as long as we need. We prepare the cream: separately we put the milk to boil. While it is warming, beat the eggs with sugar and flour until smooth. When the milk boils, add the egg mass to it, while intensively whipping the resulting cream with a whisk or mixer. Turn down the heat and bring to a boil, without ceasing to stir. After cooling, rub the zest of one lemon into the cream and then whisk together with softened butter. We send it to freeze in the refrigerator for half an hour. We take a rectangular shape with high walls, put a layer of custard cakes on its bottom, spread them liberally with cream on top, close with a second layer of cakes, which are also coated with cream. Etc. When all the cakes are in the cake, we put our delicacy in the refrigerator (such food should generally stand only in a cold place, otherwise it will spread).