I don’t think there is a more cunning way to order that specific masterpiece…lol. As soon as you want cheese you’re locked out of the a la carte ordering since you can’t order a slice of cheese by itself. For someone who wanted a dairy free version, however, you could order the two 1/4 patties, sausage, and egg a la carte and it should be cheaper.
You can order bunless via the kiosks but not the added egg and sausage. They don’t give you the same degree of flexibility at the kiosks because they don’t want to encourage every order to be something special. It does slow things down in the kitchen and they do still want to be “fast” food.
The thing is, a keto option at McDonald’s is fairly healthy. The beef is 100% beef, the grill has no vegetable oil, the egg is just an egg. Admittedly, the cheese is processed on the 1/4 pounder, but if you upgrade to the 1/3 pound Angus burger you can get a premium cheese. Basically, what @Gaff ordered is just meat, cheese and egg. It’s not unhealthy just because it came from McDonald’s.
Same with their grilled chicken salads. Cheese, fresh vegetables, grilled chicken. All good stuff.