Using your mixer bowl, dissolve the yeast and sugar in the warm water and let stand for five minutes, or until foamy. (if your bowl is chilled or your room is cool this could take longer)
Add butter, salt & 3 cups of the flour, and mix until combined.
Add additional flour, 1/4 cup at a time, until the dough pulls away from the sides of the bowl and is slightly sticky to the touch. (do not add too much flour!)
Let the mixer knead 3-5 minutes, until smooth.
Cover with plastic, place in a warm spot and let rise 20 minutes.
Preheat oven to 400 degrees & spray a 9 x 13 casserole dish with cooking spray.
Punch down the dough & divide it into 20 equal-sized pieces.
Roll each piece into a ball and space evenly in the prepared pan.
Brush with melted butter, sprinkle with sea salt and let rise for an additional 15-20 minutes.
Bake 13-15 minutes, or until golden brown. ( you can turn on the broiler for about 1-2 minutes at the end to get a more golden top)
Remove and brush with butter.
Let cool slightly before serving.