Step 1

Whisk together all of the ingredients in a medium bowl or a large glass measuring cup.

Step 2

Prepare the ramekins with nonstick spray. Pour about 1/2 cup of the mixture into each ramekin. Cover each ramekin tightly with a small piece of aluminum foil.

Step 3

Pour a cup of water and the wire rack into the insert pot of your pressure cooker. Put three ramekins on the rack. If you have another similar rack, place it on top of the ramekins and stack the other ramekins on top.

Step 4

Close the lid and the steam valve. Set the cooker to high pressure for 8 minutes. Let the cooker release pressure naturally for 15 minutes before releasing any remaining pressure manually.

Step 5

Carefully remove the ramekins from the cooker and let them sit, covered, until they’re cool enough to handle. Transfer them to the fridge and chill for at least 4 hour or until completely cold.

Step 6

A few minutes before you're ready to serve the cups, make the fluff by putting the egg whites, sweetener, and cream of tartar in a large heat-safe bowl. Place that bowl on a saucepan with an inch or two of water in the bottom. Cook over medium-high heat, whisking, until the sweetener is dissolved and the mixture is warm to the touch.

Step 7

Transfer the bowl to a flat work space and beat with a hand-held mixture for about 5-7 minutes until the whites are fluffy and soft peaks form. Add the vanilla and salt and beat until combined.

Step 8

Immediately top each cup with a big spoonful of the marshmallow fluff and toast it with a hand-held kitchen torch or under an oven broiler for just a few minutes.