Combine the flour, sugar, salt, and yeast together in a large mixing bowl or the bowl of a standing mixer fitted with the dough hook. Add the buttermilk and stir with a rubber spatula or mix on medium speed until a rough dough comes together.
Knead the dough until it is smooth, 8 to 10 minutes on medium-low speed. It will be a fairly stiff dough. Cover the bowl with plastic wrap and let stand at room temperature until it doubles in size, 1 to 1-1⁄2 hours.
Grease a baking sheet and then dust it with cornmeal. Turn the dough onto a floured countertop and divide it into 10 equal pieces. Round each piece into a ball and place the balls on the prepared baking sheet. Sprinkle the tops of the dough balls with more cornmeal and cover loosely with plastic wrap. Let stand at room temperature until puffy and almost doubled in size, 1 to 1-1⁄2 hours.
Heat the oven to 350°F. Place a clean baking sheet in the oven. Heat a cast-iron griddle or skillet on top of the stove over medium-low heat.
Melt a teaspoon or two of the butter on the preheated griddle. Coat your baking rings with butter and place as many as will fit on the hot griddle. Gently place a ball of dough into each ring on the heated griddle and cook until the bottoms are well-browned, 8 to 10 minutes. Carefully flip each muffin in its ring and cook until golden on the other side. Take care not to turn the English muffins too soon. You want to wait until they are well set, or they might collapse.
As the muffins are browned, place them on the baking sheet in the oven and bake until they are cooked through, 6 to 8 minutes. Transfer the fully baked muffins to a wire rack as they are cooked through.
Repeat with the remaining muffins, adding more butter to the pan as needed and transferring the griddled muffins to the oven to finish baking. Let the muffins cool completely on the rack before serving. “Luxury” English Muffins are best eaten on the day they are made. For longer storage, freeze in a zipper-lock plastic bag for up to 1 month. To defrost, place on the countertop for 15 to 30 minutes, and reheat in the oven at 350°F for 5 minutes before serving.