Pre-heat the oven to 375 degrees Fahrenheit (180 ºC).
In a stand mixer beat the eggs, sugar and salt for about 10 minutes. It should triple its volume. Turn off the mixer and then add the flour mixing with a silicon spatula with slow swirl movements until is well combined. Pour batter into prepared 8x8 inch pan and bake for about 15 minutes and make sure is done inserting a toothpick. Let it cool in a cooling rack while making the cream.
In a medium pot, pour the condensed milk and egg yolk. Mix the milk and the cornstarch well. Pour it into the pot with the condensed milk and mix. Bring to a simmer over low heat while constantly mixing with (spoon or whisk) to avoid scorching until it’s thickened. It is suppose to be pretty thick. Then put it away for a while.
Cut the cake in small dices.
In a large clear bowl make a bed of cake dices. Then add a layer of cream and then cover the cream with mix berries. And repeat cake, cream and finish with whole strawberries and raspberries to decorate.
Leave it on the fridge for a couple of hours.
Serve and enjoy!!!