In a large bowl, whisk together your fed sourdough starter with warm water until fully combined.

Gradually add all-purpose flour, granulated sugar, softened unsalted butter, a large egg, and salt into the mixture.

Stir with a wooden spoon until a shaggy dough forms, which should take about 5 minutes.

Transfer the shaggy dough onto a lightly floured surface and knead for 5 to 8 minutes until it becomes smooth and elastic.

Lightly oil a large bowl and place your kneaded dough into it, turning once to coat.

Cover the bowl and let it rise until it has doubled in size, about 3 to 4 hours.

Once the dough has risen, gently punch it down and turn it onto a floured surface.

Roll the dough out to a thickness of about ½ inch and cut out muffins with a 3-inch round cutter.

Place the cut muffins on a cornmeal-dusted baking sheet, cover, and let them rise for an additional hour.

Heat a skillet over medium heat and carefully transfer the risen muffins onto it.

Cook them for 3 to 4 minutes on each side until golden brown and reach an internal temperature of 190°F.

Transfer the muffins to a wire rack to cool.