Whip the egg yolks well with half of the butter, half of the sugar, the lemon juice and apinch of salt.
Mix flour and milk, little by little, into the egg-yolk mixture. Let the dough rest for a couple of hours.
Preheat oven to 375°F. Whip the egg whites with the rest of the sugar till they form peaks.
Just before baking, gently fold the egg whites and the raisins into the batter.
Spread the rest of the butter in a baking pan 12 by 8inches. Heat the pan until the butter reaches frying temperature. Pour in the batter.
Bake in the preheated oven for 40 to 45 minutes. After about 10 minutes, when the batter begins to become solid on the bottom of the pan, scrape it and with a chopping motion slightly break the dough. You may have to do this several times to get the uneven broken-up texture characteristic of this dish.