Pour condensed milk into a deep bowl, add 1 egg, stir. Pour in flour and baking powder. Mix everything until smooth and elastic. Place the dough on a surface sprinkled with flour. Roll it into a sausage. Cut into 6 equal-sized pieces. Roll the resulting pieces into thin sheets, based on the diameter of the frying pan. Heat the frying pan. Fry the layers of dough on both sides.
Prepare the cream. Mix 2 eggs, flour and sugar in a saucepan. Pour milk into the mixture, one fifth of the total amount. Put the saucepan on the fire. Stir the mixture until smooth, adding the remaining milk in portions. Remove the cream from the stove. Add butter and stir.
Assemble the cake. Cut out equal-sized layers from the cooled flat cakes. Place one layer on the bottom of the pan and grease it with cream. Cover with the next layer. Grease with cream. Repeat with all the layers except the last one. Put it on top without greasing. Put the cake in the refrigerator for 3 hours so that it soaks in the cream.