Sift the flour and baking powder and leave them aside. Beat the butter and sugar until whitened (about 2 minutes). Add the salt, vanilla and condensed milk and whip until the mixture becomes homogeneous.
On a low mixer setting, add the flour in 3 lots. Once beaten well, start adding the eggs one by one and beat again until everything is homogenized.
Pour the mixture into a greased and lightly floured cake form and put it to bake in a preheated 347°F (175 °C) oven for about 1 hour (or less).