For sponge: Whisk flour, water, yeast and honey in large bowl until smooth. cover with plastic. Let stand in warm draft-free area 1 hour.
For dough: Stir down sponge, using wooden spoon. Blend in milk, butter and salt. Mix in enough flour 1/2 cup at a time to form soft dough. Knead on floured surface until smooth and no longer sticky, adding more flour if necessary, about 10 minutes.
Grease large bowl. Add dough, turning to coat entire surface. Cover bowl with plastic. Let rise in warm draft-free area until doubled, about 1 1/4 hours.
Grease eight 2 1/2 x 4 1/2-inch loaf pans. Gently knead dough on lightly floured surface until deflated. Pat out to 3/4 inch-thick rectangle. Cut into 8 even pieces. Pat each out into 4x7-inch rectangle. Spread 1 ounce chocolate on short end of each. Roll up jelly roll fashion. Pinch seam and ends to seal. Arrange seam side down in prepared pans. Cover with kitchen towel. Let rise for 15 minutes to lighten.
Preheat oven to 375 F. Brush loaves with egg glaze and sprinkle with sugar. Bake until light brown and loaves sound hollow when tapped on bottom, about 30 minutes. Immediately remove from pans. Cool on racks 10 minutes. Serve loaves hot.
adding chopped chocolate.