Soak the raisins in lukewarm water for 20 to 30 minutes.
Put the sugar and softened butter in a mixing bowl and beat them with a whisk to a foamy consistency.
Add the egg yolks to the bowl and then the milk, in a very thin, slow stream, mixing all the ingredients thoroughly.
Mix in the 1⅔cups flour a little bit at a time.
Drain the raisins and pat them thoroughly dry with kitchen towels. Dust them with the 2tablespoons of flour, shake them in a strainer to remove excess flour, and add them to the mixing bowl, together with the cocoa and the pine nuts. Mix until all the ingredients are well amalgamated.
Whip the egg whites with a pinch of salt until they form stiff peaks, then fold them lightly into the mixture in the bowl.
Lightly grease the bottom of a 10-inch springform pan with butter, dust it with flour, then turn it upside down and knock it once or twice against the work counter to shake away excess flour. Pour in the cake batter and level it with a spatula. Place the pan in the uppermost level of the preheated oven. Bake for 50 minutes, or until a toothpick inserted into the cake comes away clean.