In a medium-sized bowl, whisk together the flour, salt, sugar, baking soda, and yeast.
In a small or medium saucepan, heat the milk and butter together over medium heat, whisking occasionally, until the butter has melted.
Let the milk cool until it’s lukewarm (you can speed this up by placing the liquid in the fridge for several minutes).
Place the dry ingredients in a stand mixer bowl fitted with the dough attachment, then turn on the mixer to low speed.
Add the milk mixture* and egg, mixing until the dough comes together.
Turn the speed up to medium and mix for an additional minute. (Note: the dough will be a bit sticky. If it’s too sticky to handle, add an additional 1-2 tablespoons of flour and mix until just combined).
Transfer the dough to a lightly floured surface, then roll out to around ½-inch thick.
Use a 3 ¾-inch cookie cutter to cut rounds from the dough, re-rolling as needed.
Place the dough on a baking sheet lined with parchment paper and dusted with semolina flour. Cover the baking sheet loosely with a dish towel and set aside to rise in a warm place until doubled in volume (approx. 45-90 minutes).**
Place an oven rack on the center shelf and preheat the oven to 325 degrees F.
Use a nonstick skillet set over medium-low heat to cook the English muffins for 3-5 minutes per side, or until lightly crisp and browned.
Transfer back to the baking sheet and bake for 15 minutes.
Before serving, fork split the English muffins.