Preheat the oven to 325 degrees F. Butter the ramekins.
In a mixer with a paddle attachment, cream the butter with 1/3 cup of the sugar. Mix in the egg yolks; then fold in the flour (it may look curdled.) With a whisk, work in the milk, lemon juice and lemon zest.
In a standing mixer fitted with a whisk attachment, whip the egg whites until foamy. Gradually add the 3/4 cup sugar and continue whipping on medium speed until glossy. Whisk 1/4 of the whites into the lemon mixture and then fold in the remainder.
Portion the batter immediately into the buttered dishes filling 3/4 of the way full and bake immediately in a water bath covered with foil for 30 minutes. Serve warm topped with a scoop of raspberry sorbet.