In the bowl of a heavy-duty electric mixer fitted with a dough hook, combine the yeast, sugar, and warm water; stir to blend. Let stand until foamy, about 5 minutes.
Stir in the salt. Add the flour, a little at a time, mixing at the lowest speed until most of the flour has been incorporated and the dough forms a ball. Continue to mix at the lowest speed until the dough has become a sticky ball and pulls away from the sides of the bowl; about 4 to 5 minutes.
Dust the counter lightly with flour. Knead the dough by hand for a minute and form into a ball. Transfer the dough to a bowl, cover tightly with plastic wrap, and let it sit in a warm spot for 2 hours to rise.
To form the baguettes: Cut the dough into 4 equal pieces. Press each piece of dough into a rectangle and fold the long sides up into the middle. Roll each into a log, taking care to close the seam. Taper the ends by gently rolling it back and forth. Lay the baguettes on a sheet pan that is dusted with cornmeal and cover with a towel. Let the baguettes rise for another 2 hours.
Preheat the oven to 400 degrees F.
With sharp knife, make 4 or 5 diagonal slashes across the top of each loaf. Brush the tops of the loaves with milk. Bake for 40 minutes, until the bread is golden brown. Cool on a wire rack.