Measure sourdough starter into large bowl and mix in yeast, milk, and butter with warm water.
Add all-purpose flour while mixing.
Knead to form dough that is soft and elastic. (I use an electric mixer for 6-8 minutes)
Place the dough in a lightly greased bowl.
Cover for Bulk fermentation for 5-6 hours over overnight n frig.
Once dough doubles, turn it out on a floured work area.
Roll out dough ¾" thick and cut into 3" rounds.
Place the rounds onto semolina flour dusted parchment paper. Cover for 1 hr.
Preheat griddle to medium high and preheat oven to 350℉.
Grill muffins for 2 minutes on each side and transfer to a sheet pan covered with parchment.
Bake muffins in preheated oven for 20 minutes to ensure a thorough cook inside.