Beat the egg whites and set aside. Add the sugar to the egg yolks and beat until a light cream is obtained;
Add the butter and yogurt and mix. Add 3 tablespoons of jam and mix;
Add the sifted flour and mix gently. Add a small part of this mixture to the egg whites and mix, gently, from bottom to top with a spatula, until incorporating everything;
Add the two mixtures and continue stirring in the same way: gently, from bottom to top;
Place the dough in a greased pan. Reserve a small part of the dough. Spread jam over the dough. Cover with the rest of the dough;
Place inside the oven for 35/40 minutes, or until, when testing with a toothpick, it comes out cleans;
Since the jam is heavier than the dough, it will go down to the bottom of the pan. So, when turning the cake, the jam will be on top. Sprinkle powdered sugar / icing sugar, if you prefer.
