Preheat the oven to 350 degrees F.
In a large bowl, combine the yolks and sugar and whisk well until the mixture is yellow and creamy, about 1 minute.
In a separate bowl, combine the cornmeal, flour, lemon zest, baking powder, and salt and mix well. Briefly stir in the butter, then fold in the egg yolk mixture and raisins until the dough just comes together. Put the dough out onto a floured board briefly knead to form a rectangle, do not overwork the dough or it will get tough. Roll the dough out to 1/4-inch thick and cut it into 2-inch diamonds. Butter a cookie sheet and place the cookies on the sheet. Bake for 12 minutes, or until golden brown and firm. Serve hot or at room temperature.