Begin by peeling the onion and carving a hole in the center of the onion.

Place the onion on a sheet of foil.

In that hole, place the beef bouillon cube in the hole as well as the butter.

Push this down in the hole.

Add the ice cube right on top of the hole and wrap the onion up in the foil.

Repeat the steps for the additional onion.

Place each wrapped onion in the basket of the air fryer or ninja foodi and cook at 390 degrees for 20 minutes.

At 20 minutes, carefully (it's hot) pull back the foil and see if it's soft enough for your liking. If so remove and serve. If not, add an additional 5 minutes.