In a small bowl, dissolve yeast in warm water and set aside.
In a large mixing bowl, combine sugar, milk, butter, salt, and egg. Add 2 cups of flour and mix until smooth. Add yeast mixture.
Mix in remaining flour until dough is easy to handle. Knead dough on lightly floured surface for 5 to 10 minutes. Place in a well-greased bowl, cover, and let rise until doubled in size, usually 1 to 1 ½ hours.
When doubled in size, punch down dough. Roll out on a floured surface into a 15 by 9-inch rectangle. Spread softened butter all over dough. Mix brown sugar and cinnamon and sprinkle over buttered dough. Sprinkle with chocolate chips.
Beginning at the 15-inch side, roll up dough and pinch edge together to seal. Cut into 12 to 15 slices.
Preheat oven to 350°F (175°C). Place cinnamon roll slices close together in a lightly greased 9x13-inch baking pan. Let rise until dough is doubled, about 45 minutes.
Bake for 25 to 30 minutes or until nicely browned.