1Cut the beef chuck roast into 4 equal pieces and remove butcher's twine (if you want it to fall apart during cooking).
2Place the meat in the Ninja Foodi cooking pot (pressure setting).
3In a large bowl, whisk together cola, French onion soup mix, soy sauce, garlic salt, and dry gravy mix. It will be slightly lumpy.
4Pour the mixture over the meat, ensuring all pieces are well coated.
5Close the pressure cooking lid and set the valve to 'seal'.
6Cook on high pressure for 60 minutes.
7After 60 minutes, allow the pressure to release naturally (do NOT quick release) – this takes about 20-30 minutes.
8Open the lid and remove the meat. Let it rest on a cutting board.
9For the gravy: set the Ninja Foodi to Sauté mode. Whisk 1/2 cup of the hot cooking liquid with the cream of mushroom soup, then pour into the pot. Let it simmer.
10For a thicker gravy: mix 3 tablespoons cornstarch with 3 tablespoons cold water until smooth, then stir into the pot, whisking. The gravy will thicken as it cools.
11Taste the gravy and adjust salt if needed. Return the meat to the gravy to keep it moist.
12Serve the meat generously covered with gravy, alongside mashed potatoes or vegetables.