To make yeast dough, stir a pinch of sugar into warm milk and sprinkle with yeast.
Let stand 5 minutes or until the surface is frothy.
Stir gently to moisten any dry particles remaining on top.
Sift flour, remaining sugar and salt into a large bowl.
Melt margarine; cool slightly.
Lightly beat margarine and eggs into yeast mixture.
Pour into flour mixture, combining to make a dough.
On a floured surface, knead dough until smooth and elastic.
Cover and let rise in a warm place 1 hour.
Grease a 13x9-inch (33x23-cm) cake pan.
Knead risen dough lightly.
Roll out to fit bottom of cake pan.
Place dough in pan.
Preheat oven to 400°F (205°C).
To make topping, mix cream, yolks, sugar and semolina flour in a medium bowl.
Beat whites until stiff; fold in raisins.
Fold egg white mixture into cream mixture; spread over dough.
Bake 20 to 25 minutes or until filling is golden on top.
Cut into squares and serve warm.