1 C. milk
1/3 C. all-purpose flour
2 1/2 (.25 ounce) packages active dry yeast
3 t. sugar
1/2 C. warm water (110°F.)
10 egg yolks
3/4 C. butter, melted
2 t. vanilla extract
2 t. lemon zest
5 C. all-purpose flour
3/4 C. raisins
2 T. water
Warm the milk in a small saucepan until it bubbles, then remove from heat. Place 1/3 cup flour in a large bowl and pour milk over flour. Beat until smooth.
Let cool until lukewarm. In a small bowl, dissolve yeast and sugar in warm water. Pour into cooled milk and beat well. Let rise in a warm place until bubbly.
Stir 2 eggs, egg yolks, butter, vanilla and lemon rind into milk/yeast mixture. Mix in flour, 1 cup at a time, beating well after each addition. When a loose dough has formed, turn out onto a lightly floured surface and knead until smooth, about 10 minutes. Gently knead in raisins.
Lightly oil a large bowl, place the dough in the bowl and turn to coat with oil. Cover with a damp cloth and let rise in a warm place until doubled in volume, about 45 minutes. Deflate the dough and let rise again until doubled in volume, about 30 minutes.
Deflate the dough and turn it out onto a lightly floured surface. Divide the dough into 3 equal pieces and form into round loaves.
Place the loaves into well-buttered, tall, round baking pans. Coffee cans can be lined with parchment paper and used instead. Do not fill the pans more than 1/3 full.
Cover the loaves with a damp cloth and let rise until tripled in volume, about 40 minutes. Meanwhile, preheat oven to 375°F.
In a small bowl, beat egg with 2 tablespoons water. Lightly brush this mixture onto the risen loaves. Bake in preheated oven 10 minutes. Reduce oven temperature to 325°F. and bake for 30 minutes more. Reduce oven temperature to 275°F. and bake for another 15 to 20 minutes, until golden brown.
Let loaves stand 5 to 10 minutes before removing from pans. Transfer loaves very gently onto a cloth-covered pillow (never a hard surface as this may cause the babka to settle or fall). Change position of loaves during cooling period.
Yield: makes 3 loaves 6 inches in diameter.