Make the dough: Combine the yeast and warm water in the bowl of a stand mixer fitted with a dough hook attachment. Stir until the yeast has been sufficiently dissolved.
Warm the buttermilk in a small pan over low heat or microwave until it is just lukewarm and no longer cold from the refrigerator. Stir the buttermilk into the yeast/water mixture.
Add the flour, sugar and kosher salt to the wet ingredients in the bowl, turn the mixer on to medium-low speed and process just until a shaggy, loose dough comes together, about 3 to 4 minutes.
With the mixer still running, add the room-temperature butter into the bowl one tablespoon at a time until each is almost fully incorporated. Knead the dough on medium-low speed for 7-8 minutes, or until it is tacky but no longer sticky and holds it’s shape. The dough will never fully collect from the side of the bowl, but will begin to slowly climb up the hook attachment.
Lightly spray a large mixing bowl with vegetable oil and scrape the dough from the mixer into it. Cover the bowl with plastic wrap and allow it to rest and expand for about 1 hour.
After the dough has risen, place the bowl into the refrigerator for 30 minutes to 1 hour to chill, thus making the dough easier to handle.
Shape the muffins: Line a rimmed baking sheet with parchment paper and evenly scatter on a 1/4-inch thick layer of cornmeal. Set aside.
Scatter your work surface with a very fine dusting of flour and lightly flour your hands as well. Turn the dough out onto the work surface and knead it a few times to deflate it. Shape it into a fat, smoothish log.
Pinch off a clump of dough slightly larger than a golf ball (about 40-50 grams if you have a kitchen scale) and lightly roll the piece of dough into a neat ball, applying as little pressure as possible. As you shape each ball, transfer the balls of dough, one by one, to the cornmeal-lined baking sheet, then pat it down gently to adhere some of the cornmeal.
Grab the ball very gently by it’s sides and flip it over, gently adhering cornmeal to the other side. Leave about an inch of space between each future muffin to allow for rise as they may need. From here you can proceed with the recipe directly or refrigerate the baking sheet, wrapped in plastic wrap for up to three days.
Griddle-bake the muffins: Preheat the oven to 250°. Warm a cast-iron skillet or griddle over very low heat for 5 minutes. Sprinkle the skillet with a light, even layer of cornmeal.
Grab one of the proofed muffins by it’s uncornmealed sides and dust off any excess cornmeal clinging to their tops and bottoms. Working in batches, transfer the muffins to the griddle. Griddle-bake the muffins very slowly, allowing a full 4-5 minutes or until their tops are slightly puffed up. Using an offset spatula, carefully flip each muffin and allow to griddle-bake on their other side for another 4-5 minutes. You should notice the muffins beginning to form a noticeable skin. Flip them again and cook for another 5-6 minutes and then flip them again. This may seem tedious and unnecessary, but this process aids in the development of a light-as-air interior. At this point you can slightly bump up the heat and gently toast their tops and bottoms, flipping every 2-3 minutes or until they are patchy brown and uniformly golden.
Place the muffins on a baking sheet lined with parchment paper and bake them in the oven for 10-12 minutes to finish cooking. Remove from the oven and let them cool on the baking sheet until cooled to room temperature.
To Serve: Using a fork, puncture an equator of tiny holes around the middle of each muffin and then pry apart the two halves.
Warm 2 tablespoons of the butter in large, nonstick skillet over low heat. Rub the inside of a 3-inch ring mold or cookie cutter with some butter or spray liberally with nonstick cooking spray. Repeat with the remaining molds and set them inside of the skillet to heat up slightly.
Carefully crack each of the four eggs into their own small bowls or teacups. Taking your time, and ensuring that each ring mold is sitting squarely on the base of the skillet, pour the eggs from their cups into the ring molds. Season the eggs to taste with salt and black pepper. Now is the time to break the yoke if you want. Cover the skillet and allow the eggs to gently cook until they have set and are no longer runny, about 8-10 minutes.
Meanwhile, lightly toast the English muffins and warm the Canadian bacon in another small skillet set over medium heat.
When the eggs are cooked, carefully remove the molds from the skillet. If the eggs do not release on their own from the molds, run a small paring knife along the base of the mold to free any stuck edges.
Compose the sandwiches by lightly buttering each half of the English muffins then layer a slice of American cheese, then the egg followed by a slice of the warmed Canadian bacon. Top with the other half of the muffin and serve immediately.