Warm the milk. Heat the milk until just warm to the touch, not hot. If using active dry yeast, sprinkle it over the warm milk and let it sit for 5–10 minutes until foamy.

Mix the wet ingredients. In a large bowl, combine the sourdough discard, warm milk (with yeast if using active dry), melted butter, and sugar. Stir until smooth.

Add the dry ingredients. Add flour and salt. Stir with a sturdy spoon until no dry spots remain. The dough will be soft and sticky—this is what you want.

First rest (bulk rise). Cover the bowl and let it rise at room temperature for 60–90 minutes, until puffy and expanded. For deeper flavor, refrigerate overnight and continue in the morning.

Stir in baking soda. Sprinkle baking soda over the dough and fold it in with a spatula. The dough will loosen slightly and become bubbly. Rest for 10 minutes.

Prepare your surface. Lightly dust a baking sheet with cornmeal or semolina. Also dust your work surface with flour or cornmeal to help with shaping.

Shape the muffins. Gently turn the dough onto the floured surface. Pat it into a 3/4-inch thick slab. Use a 3-inch round cutter to cut circles. Transfer to the prepared sheet and lightly dust the tops with cornmeal. Gather scraps, gently press, and cut again. You should get about 8–10 muffins.

Final proof. Cover loosely and let the rounds rest 20–30 minutes, until slightly puffy. They won’t double, but they should look lighter and airy.

Preheat the skillet. Heat a heavy skillet or griddle over medium-low. Lightly grease with a thin film of oil or butter. Sprinkle a little cornmeal onto the hot surface if you like extra crunch.

Cook low and slow. Place muffins in the skillet, leaving space between them. Cook for 6–8 minutes per side, adjusting heat to keep the bottoms from burning. They should turn a deep golden brown and feel springy. If they brown too fast, lower the heat and extend the time so the centers cook through.

Finish in the oven (optional). If they’re browned but still feel very soft in the center, place them on a baking sheet and bake at 350°F (175°C) for 5–8 minutes.

Cool and split. Cool on a rack for at least 15 minutes. For classic nooks and crannies, split with a fork by poking all the way around the edge and pulling apart, then toast before serving.