Melt the butter in a small pan, using a bain-marie, and then leave it to cool down. Beat the egg yolks with the sugar thoroughly, keeping the whites to one side; add the butter and – a little at a time – the flour sifted together with the baking powder, taking care to mix well. Beat the egg whites until “stiff”: tip the bowl up vertically, if the whites don't drop out you've done a good job! Mix them with the beaten yolk, a few spoonfuls at a time stirring from bottom to top, and add 50 g of pine nuts as well. When the mixture is smooth and homogeneous, pour it into a round cake tin (28 cm in diameter) that you have buttered and floured well, level the surface and sprinkle the remaining pine nuts over it. Bake in a preheated oven, at 180 °C, for 45 minutes. While it’s cooking, the “Mantovana” will fill the kitchen, or even the whole house, with its aroma. Fragrances that take you back in time, to days gone by. This cake can be enjoyed with a little glass of Vin Santo or with a cup of tea, according to the time of day, it’s also delicious at breakfast with hot (or cold) milk and perfect for children’s taste as well.