Combine milk, yeast, and 1/3 cup sugar in bowl of a stand mixer; let stand 5 minutes or until foamy. Gradually add 1 cup flour, beating at low speed until blended; scrape down sides. Add salt and 1 cup butter; beat at low speed until smooth. Add eggs, 1 at a time, beating until incorporated after each addition and scraping sides of bowl as needed. Gradually add remaining 3 1/2 cups flour, beating until blended. Increase speed to medium, and beat until dough forms a ball and begins to pull away from sides. Beat dough 2 more minutes or until smooth and elastic. Turn dough out onto a lightly floured surface, and knead 3 minutes.
Place dough in a large greased bowl, turning to grease top. Cover with plastic wrap, and let rise in a warm place (80° to 85°), free from drafts, 1 hour or until doubled in bulk. Punch dough down, and turn out onto lightly floured parchment paper. Roll dough into a 12- x 18-inch rectangle.
Brush 6 Tbsp. soft butter over dough; sprinkle with chocolate and 1/2 cup sugar. Roll up dough, jelly-roll fashion, starting at 1 long side. Press edge to seal, and place dough, seam side down, on parchment paper.
Transfer parchment paper with dough onto a baking sheet. Shape rolled dough into a ring, pressing ends together to seal. Cut ring at 2-inch intervals, from outer edge up to (but not through) inside edge. Gently pull and twist cut pieces to show filling. Cover dough.
Let rise in a warm place (80° to 85°), free from drafts, 1 hour or until doubled in bulk. Preheat oven to 350°. Uncover dough. Melt remaining 2 Tbsp. butter; brush over dough. Bake 30 to 40 minutes or until golden. Cool on pan 10 minutes. Drizzle Easy Vanilla Glaze over warm bread.
Freshly Baked Bread: Make the dough (through Step 4) a day ahead. Chill overnight. Let the dough come to room temperature and rise in the morning. Then bake and serve.
Citrus-Cranberry Wreath: Omit chocolate and Easy Vanilla Glaze. Soak 1 cup sweetened dried cranberries in 1 cup boiling water 15 minutes; drain and pat cranberries dry. Prepare Breakfast Wreath recipe as directed through Step 3, sprinkling cranberries over dough and 1 Tbsp. lightly packed orange zest over cranberries before rolling. Proceed as directed in Steps 4 and Beat together 3 oz. softened cream cheese and 1 Tbsp. softened butter in a medium bowl at medium speed with an electric mixer. Gradually add 2 cups powdered sugar to cream cheese mixture alternately with 2 Tbsp. fresh orange juice, beating at medium speed after each addition. Add up to 2 Tbsp. fresh orange juice, 1 tsp. at a time, until desired consistency is reached. Drizzle over bread. Hands-on 25 min.; Total 3 hours, 40 min.