In a bowl, combine warm milk and sugar. Sprinkle the yeast on top and let it sit for about 5-10 minutes until frothy.

In a large mixing bowl, combine the all-purpose flour, whole wheat flour, and salt. Stir well to blend the ingredients evenly.

Once the yeast is activated, pour it into the dry mixture along with the melted butter. Stir until the mixture forms a dough.

Turn the dough out onto a lightly floured surface and knead for about 5-8 minutes until smooth and elastic.

Place the dough in a lightly greased bowl, cover with a cloth, and let it rise for about 45 minutes, or until doubled in size.

After the dough has risen, turn it out onto a surface dusted with cornmeal. Roll out to about 1-inch thick and cut out circles using a round cutter.

Place the cut muffins on a lightly cornmeal-dusted tray. Cover and allow them to rise for another 30 minutes.

Preheat a skillet over medium heat and cook the muffins for about 7 minutes on each side, or until golden brown.

Once cooked, let them cool on a wire rack before serving.