INGREDIENTS
2 cups milk, warmed to 110¡ãF
5 packages active dry yeast
1 1/2 cups plus 1 tablespoon sugar
7 cups plus 2 tablespoons all-purpose flour
1 teaspoon salt
1 tablespoon grated lemon zest
3/4 cup golden raisins
1 teaspoon pure vanilla extract
10 large egg yolks, lightly beaten
3 large eggs
1/2 cup plus 1 tablespoon unsalted butter, melted

DIRECTIONS
1. Make the dough: Coat a large bowl with oil and set aside. Combine the milk, yeast, the 1 tablespoon sugar, and 1 cup flour in a small bowl and set aside. In the bowl of a standing mixer fitted with a dough hook, combine the remaining 6 cups flour, remaining sugar, salt, lemon zest, and raisins. With the mixer on low speed, add vanilla, egg yolks, 2 eggs, and the yeast mixture. Mix on low speed until a smooth, elastic dough forms ¡ª about 10 minutes. Add the 1/2 cup butter and mix for 5 more minutes. Transfer the dough to the prepared bowl, turning to coat all sides with oil. Cover the bowl with a clean, damp kitchen towel and set dough aside to rise in a warm, draft-free place until it doubles in volume ¡ª about 1 hour.

2. Shape the loaf: Coat two 8-inch round by 4-inch-deep baking dishes with remaining butter and lightly dust with the 2 tablespoons flour, shaking out any excess. Set aside. Punch down the dough, transfer it to a lightly floured surface, and divide it in half. Shape each half into a ball and place them in the prepared dishes. Cover with a clean, damp kitchen towel and let rise in a warm place until dough doubles in volume ¡ª about 1 hour. Preheat oven to 350¡ãF.

3. Bake the bread: Beat the remaining egg and lightly brush the top of babkas. Bake in the lower third of the oven for 15 minutes. Reduce the oven temperature to 300¡ãF and continue to bake until the loaves are golden and sound hollow when tapped ¡ª about 40 more minutes. Transfer the finished loaves to a wire rack to cool.