Mix the active sourdough starter and warm milk in a large bowl.
Whisk together flour, sugar, salt, and baking powder in another bowl.
Gradually add dry ingredients to the wet mixture to form a soft dough.
Knead the dough gently for about 5 minutes.
Cover the bowl and let it rise for 1-2 hours until doubled in size.
Turn the dough onto a floured surface and shape it into a log.
Cut the log into pieces and shape each into round muffins.
Dust with cornmeal and place on a baking sheet.
Let rise for another 30 minutes before cooking.
Cook each muffin in a preheated skillet for 5-7 minutes on each side until golden brown.