Step 1

Fill a medium to large pot with 1 inch of water and bring to a simmer.

Step 2

In a large heat-proof bowl (or the bowl of your stand mixer), whisk together egg whites, sugar, cream of tartar, and salt.

Step 3

Place bowl over the simmering water on the stove, making sure the bottom of the bowl is not touching the water. Heat, whisking constantly until eggs reach 120°F.

Step 4

Remove bowl from heat and use your hand mixer or electric mixer to beat the egg whites on high for 5 minutes or until light and fluffy with peaks that mostly hold their shape.

Step 5

If desired, add vanilla extract and beat for another 30 seconds until well-mixed.

Step 6

Transfer immediately to a piping bag or use a large plastic bag with the tip cut off to pipe onto cupcakes.

Step 7

Very carefully brown under your broiler or toast with a kitchen torch. This step is optional, but the frosting is quite sticky until toasted.