In a large bowl combine fed sourdough starter, with 2 cups of flour, and the cup of milk.
Stir to incorporate, and cover with a dish towel.
All to sit for at least 8 hours, or overnight. I start mine at night, and it's ready by morning.
Add remaining ingredients to your raised sourdough mixture.
Place the dough on a lightly floured surface, and knead for about 5 minutes, or until the dough is uniform and smooth.
Roll the dough out to about 1" thickness, and cut our muffins. (I used a glass that I lightly dusted the rim with flour.)
Transfer to parchment paper dusted with cornmeal.
Allow the muffins to rest for 45 minutes.
Preheat a cast iron skillet over medium low heat. Preheat oven to 350 F
Cook muffin on each side until nicely browned, turning once. If the muffin isn't quite cooked inside, place them in the oven for about 5 minutes to finish the insides.