1Preheat a nonstick skillet over medium heat. Place the breakfast sausage patty in the dry pan and cook until golden brown and cooked through, about 2 to 3 minutes per side. Transfer the cooked sausage to a plate and keep the skillet on the heat with the rendered fat.
2Spray a 3 to 4-inch ring mold or biscuit cutter with cooking spray and place it in the skillet with the sausage drippings. Crack the egg directly into the ring mold, breaking the yolk gently with a fork or spatula to create an even, flat patty. Season with a pinch of salt and black pepper.
3Cook the egg until the bottom sets, about 1 to 2 minutes. Add 1 tablespoon of water around the ring mold (not directly on the egg), then immediately cover the skillet with a lid to steam the egg until just set but still slightly soft, about 1 to 2 minutes more. Remove the ring mold carefully and transfer the egg to a plate.
4Split the English muffin in half and spread the remaining butter on the cut sides. Toast the muffin halves buttered-side down in the same skillet or in a toaster until lightly golden, about 1 to 2 minutes.
5Assemble immediately: Place the bottom English muffin half on a plate, add the cooked sausage patty, top with the American cheese slice, add the cooked egg round, and crown with the top muffin half. The residual heat will melt the cheese perfectly.
6Serve immediately while hot for the authentic fast-food experience.