The sandwiches come overflowing with cheese, at least judging from the promotional photo published by McDonald's Hong Kong. Thrillist reached out to McDonald's for more information on these toasted sandwichettes, but they're both essentially pressed grilled sandwiches. The Champignon is filled with champignon mushrooms, sweet corn, and melted white cheese (riffing on cheese corn for lovers of Korean BBQ). The Bacon, Macaroni & Cheese explains itself as adequately as any sandwich ever has. Combined, they put the American McCafé menu to shame by comparison.
In the United States, both mac & cheese and grilled cheese sandwiches have actually been a part of McDonald's menu lore for quite some time -- long enough for us to do taste tests of both items in 2015. The verdict on the grilled cheese, a "secret menu" item which really just amounts to two McDonald's hamburger buns and a slice of American cheese, was a resounding "No." Later that year, while the chain's Cleveland locations tested its mac 'n' cheese in Happy Meals, an editor with a niece and nephew described it as "an adequate Happy Meal option for kids who don't like meat."
McDonald's Hong Kong's grilled cheese toasties sound way tastier than that, but sadly we can expect these to arrive in the United States right around the same time McDonald's Japan's deep-fried mac 'n' croquette burgers do, aka never. An Asian vacation looks better and better by the minute, y'all.