Make the Keto English muffin by preparing a ceramic or heat-safe ramekin with butter. Rub the first amount of butter all over inside the ramekin until a thin layer of soft butter is coating the ceramic. Keep the buttered ramekin in your refrigerator while you prepare the other ingredients. If you don’t own a ramekin, you may also use a heat-safe coffee mug.
Whisk together the egg, heavy cream, almond flour, salt, baking powder, and erythritol in a mixing bowl. Melt the second amount of butter, and whisk it into the mixture. Pour the batter into the buttered ramekin, and microwave the batter for 90 seconds. When the English muffin is cooked, let it cool for 1-2 minutes before flipping it out onto a clean surface to cool. The English muffin will appear very spongey at first, but it will become firmer as it cools.
To make the sausage patty for the sandwich, press ground Italian sausage together into a patty. Use the base of your ramekin as a reference for what size you should make the patty. Make the sausage patty just a little wider to make up for shrinkage during cooking. Heat the olive oil in a small pan over medium-high heat, and cook the Italian sausage patty on one side for about 4 minutes. When you flip the patty over, lay a slice of cheddar cheese on top to melt. Finish cooking the sausage patty for another 4-5 minutes, and set it aside to rest temporarily.
Grab the ramekin you used to make the English muffin, and wipe out any crumbs. Give the ramekin a light coating of pan spray. In a clean bowl, whisk the second egg, heavy cream, and salt. Pour the mixture into the ramekin, and cook your egg patty for 40-45 seconds. After letting the egg cool for about 1 minute, flip it out just like you did the English muffin.
To assemble the sandwich, slice the English muffin in half. Mix together mayonnaise and dijon mustard, and spread it across the bottom half of the English Muffin. Transfer the sausage patty with cheese on top of the sauce. Transfer the egg patty on top of the sausage patty, and place the other English muffin half on top. If necessary, you can keep the sausage muffin sandwich together with a toothpick.
Mix thawed cauliflower rice from frozen with egg yolk, mayonnaise, salt, pepper, and nutritional yeast to make the hashbrown mixture. Heat the avocado oil in a cast-iron or non-stick skillet on medium-high heat. When the oil is hot, pour 2-tablespoon portions of hashbrown mixture into the skillet to make approximately 4 hashbrowns per serving. Cook the hashbrowns for 2-3 minutes per side, not flipping them over until they naturally release from the skillet. Serve hot with your sausage muffin sandwich.