Step 1

To make your overnight sponge: combine discard with flour and milk. Stir well to combine, and cover loosely with plastic. Rest on countertop overnight, or for up to 18 hours.

Step 2

Dust baking sheet with cornmeal; set aside.

Step 3

Add flour, sugar, salt, and baking soda to overnight sponge, and stir well to combine. The consistency should be like bread dough, and highly depends on the hydration of your starter discard. If needed, add more flour or more milk a little bit at a time to achieve this consistency.

Step 4

Mix in stand mixer with dough hook on low for 2-3 minutes, or by hand on a floured surface for 4-5 minutes. The dough should be the consistency of a soft bread dough, very slightly sticky. Add more flour or milk to achieve this consistency.

Step 5

Lightly dust a rolling pin with flour and roll out dough to 1/2" to 3/4" thickness. Cut muffins using a biscuit cutter or cup rim, dusted with flour. Push straight down; do not twist!Combine remaining dough into a ball and let rest 10 minutes. Then roll out and cut as above, getting as many muffins from the dough as possible.

Step 6

Transfer cut muffins to cornmeal-dusted baking sheet and let rest for 45-60 minutes.

Step 7

If you're cooking on a cast iron skillet, preheat your skillet over low or medium-low heat for several minutes (better to start your heat on the low side than on the high side!). Place muffins in skillet, six at a time, and cook for 5-7 minutes or until golden brown. Check undersides every minute. Dust tops lightly with cornmeal and flip, cooking 5-7 minutes more.

Step 8

If you're cooking on an electric griddle, preheat to 300°F. Place muffins on griddle and reduce heat to 275°F. Cook for 3-5 minutes. Dust tops lightly with cornmeal then flip, cooking for 5-7 more minutes.

Step 9

Serve warm, or toast before serving if cooled.