Step 1In the bowl of a stand mixer, whisk together 3 1/2 cups (15.75 ounces) of the bread flour, sugar and yeast.
Step 2Switch to the paddle attachment. With the mixer on low, slowly beat in the melted butter, followed by the milk to form a soft dough. Switch to the dough hook attachment, and beat in the salt. Continue mixing the dough, adding additional bread flour 1 tablespoon at a time until the dough is smooth and just begins to pull away from the sides of the bowl, about 7 minutes on medium-low speed (you may not need to add all of the flour). At this stage, the dough will be firm yet moist and somewhat sticky.
Step 3Turn the dough out into a lightly oiled large bowl. Cover the bowl with plastic wrap and refrigerate overnight (this slows the proofing process and allows the flavors to develop).
Step 4About 2 hours before cooking, remove the dough from the refrigerator, punch it down and set it aside to come to room temperature.
Step 5Place the cornmeal in a medium bowl. Using greased hands, divide the dough into 12 even portions, about 2 3/4 ounces each. Gently form each portion into a ball, and roll the balls in the cornmeal to lightly coat on all sides. Working with one ball at a time, flatten each ball into a disk about 3 1/2 inches in diameter and one-half-inch thick. (If the dough starts to spring back, set it aside and move onto the next ball to give the dough time to relax). Place the disks on a lightly greased parchment-lined baking sheet.
Step 6Place the sheet in a warm place until the disks are puffed and risen to about 1 1/2 times their original height (watch that the disks do not over-proof or they will flatten as they bake), 15 to 30 minutes.
Step 7Heat a griddle or a cast iron skillet over medium-low heat (don't heat the griddle too hot or the English muffins will brown before they are fully cooked on the inside). Very lightly grease the griddle, then gently place the muffins on the griddle, leaving a little space between each one so you have enough room to check them and flip them as needed.
Step 8Cook the muffins on one side for 5 to 8 minutes until set and lightly browned, and the muffins have risen. Using a metal spatula, gently flip each muffin to cook on the other side. Do not press the muffins down as you flip them or they will flatten; simply leave them to cook. Continue to cook the muffins until the other side is set and lightly browned, about 5 minutes more.
Step 9Cool the muffins on a rack before splitting and serving.