In a small bowl, combine yeast with 1/4 cup of milk and 1/4 tsp of sugar. Cover and let it sit for 5-10 minutes, until frothed (to proof).
In the bowl of a stand mixer, fitted with the hook attachment, combine 4 cups of flour, salt and sugar. Add frothed yeast mixture, milk, butter and egg. Stir to combine.
With the mixer on medium, knead for 5 minutes, until the dough pulls away from the sides of the bowl. Dust a working surface with some flour and transfer the dough. Knead for 2 minutes, form into a ball and transfer to a greased bowl. Cover with plastic wrap, cover with a towel and let it rise in a dark place for 1- 1 1/2 hours.
Spray a cast iron skillet (9-inch) with cooking spray.
The dough should have doubled its size by now. Remove the wrap and deflate dough. Transfer to a dusted with flour surface. Make a log and cut into 12 equal parts. Roll each one into a ball.
Place in the skillet.
Cover and let them rise for 20-30 minutes.
Preheat oven to 400 F.
Top with cheese (optional). Bake for 20 minutes, until the top i golden and toothpick inserted, comes out clean.
Serve with Kaukauna® Cheese.