FOR CHOCOLATE FILLING:
HEAT morsels, evaporated milk and 1/4 cup granulated sugar in small saucepan until morsels are melted and mixture is smooth; remove from heat. Stir in nuts, 2 teaspoons vanilla extract and cinnamon.
COMBINE 4 cups flour, 1/4 cup granulated sugar, yeast and salt in large mixer bowl.
HEAT milk, butter and water just until warm (120° F. to 130° F.) and butter almost melts. Add milk mixture to flour mixture; add eggs. Beat on low speed for 30 seconds, scraping bowl often. Beat on high speed for 3 minutes. Stir in as much of remaining flour as possible.
TURN dough out onto slightly floured surface. Knead in remaining flour to make a moderately soft dough that is smooth and elastic (3 to 5 minutes). Cover; let rest for 10 minutes.
PREHEAT oven to 375° F. Line two baking sheets with foil.
DIVIDE dough in half. Roll half of dough into 18 x 10-inch rectangle. Place dough on one prepared baking sheet. Spread half of chocolate filling lengthwise down center of dough. Cut 1-inch wide diagonal strips on both sides of dough to within 3/4 inch of filling. Crisscross dough strips over filling. Leave as long braid or bring ends together to form a ring, pinching ends to seal. Repeat with remaining dough and filling. Cover; let rise in warm place for 15 minutes.
BAKE for 35 to 40 minutes until golden brown; cool completely on baking sheet on wire rack.
COMBINE powdered sugar, 2 tablespoons melted butter and remaining vanilla extract in small bowl. Slowly add enough milk for drizzling consistency; stir. Drizzle icing over braids. Cut into slices.