To the bowl of a stand mixer, add the warm milk (make sure this is the temperature of a baby's bathwater...so as not to kill the yeast), melted butter, sugar, yeast and salt.
Add the cornstarch and 3 cups of flour to the center of the bowl and knead using the dough hook. Alternatively you can mix the ingredients together in a bowl and knead the dough on your countertop by hand for about 10 minutes. If using a dough hook, knead the dough for about 5-7 minutes, adding the extra half cup of flour as needed. You should be able to pinch off a chunk of dough, roll it into a ball in your fingers with just a little sticky residue left behind. You can check out this blog post for how to check for readiness of dough if you need some guidance.
Preheat your oven to 350 degrees.
Lightly grease a 9 by 13 pan with cooking spray.
Move the dough to your countertop and cut into twelve equal pieces.
Shape the dough into rolls one at a time. Pull up the sides of the dough into the middle while rotating the dough in your hand to form a ball. Then roll the ball on the countertop before placing on a baking sheet or dish. Watch the process here.
Cover the rolls and let them rise in a warm spot for 10 minutes.
After ten minutes, the rolls will have puffed up just a bit. If they don't look puffy, that's okay. Continue on with the recipe and bake the rolls at 350 degrees for about 22-25 minutes depending on how brown you like your rolls. For lighter rolls, bake in a glass pan. For a darker crust use a dark pan.
Once rolls have finished baking, top with melted butter and enjoy warm!
I always use SAF instant yeast in this recipe and in almost all my yeast breads.