In a large mixing bowl of a stand mixer, combine the all-purpose flour, whole wheat flour, yeast, sugar, and salt.
2¼ cups all-purpose flour, ¾ cup whole wheat flour, 1½ teaspoons instant yeast, 2 teaspoons granulated sugar, 1¼ teaspoons kosher salt
Add the warm milk and melted butter to the bowl with the dry ingredients. Stir until a dough forms.
1 cup warm milk, 2 tablespoons unsalted butter
Attach the dough hook to the stand mixer and knead the dough for about 5 minutes, or until it becomes smooth.
Place the dough in a greased bowl, cover with a clean towel or plastic wrap, and let it proof in a warm place until it doubles in size, around 1-2 hours.
Punch down the dough and roll it out on a floured surface to about ½ inch thick.
Using a round cutter, cut out muffins and transfer them to a baking sheet sprinkled with cornmeal or semolina flour.
Cornmeal
Cover with a towel and let the cut muffins proof for another 30-40 minutes.
Preheat a skillet over low heat. Cook the muffins covered for about 5 minutes on each side, until they are golden brown and sound hollow when tapped on the top.
Let the muffins cool on a wire rack. Split with a fork and toast before serving.