1. Activate the Yeast: In a large bowl, combine the warm milk, granulated sugar, and active dry yeast. Stir gently and let it sit for 5-10 minutes until foamy. This shows the yeast is active and ready to work.

2. Combine Wet Ingredients: Add the sourdough discard and melted butter to the yeast mixture. Stir until well combined. The mixture will look slightly cloudy and milky.

3. Mix Dry Ingredients and Form Dough: In a separate bowl, whisk together the all-purpose flour and salt. Gradually add the dry ingredients to the wet ingredients, mixing with a wooden spoon or your hands until a shaggy dough forms.

4. Knead the Dough: Turn the dough out onto a lightly floured surface and knead for about 5-7 minutes until it becomes smooth and elastic. It should spring back slightly when poked.

5. First Rise: Place the dough in a lightly oiled bowl, turning it once to coat. Cover the bowl with plastic wrap or a clean kitchen towel and let it rise in a warm place for 2-3 hours, or until doubled in size.

6. Shape the Muffins: Gently punch down the risen dough. On a lightly floured surface dusted with cornmeal, roll the dough to about 1/2-inch thickness. Use a 3-inch round cutter (or a clean, empty tuna can) to cut out circles. Re-roll scraps and cut more muffins until all dough is used.

7. Second Rise: Place the cut muffins on a baking sheet generously dusted with cornmeal, leaving some space between them. Dust the tops with a little more cornmeal. Cover loosely with plastic wrap or a towel and let them rise for another 30-45 minutes, or until puffy.

8. Cook on the Griddle: Heat a lightly buttered griddle or large non-stick skillet over medium-low heat. Cook the muffins for 5-7 minutes per side, or until golden brown and cooked through. They should sound hollow when tapped. Adjust heat as needed to prevent burning.