Bring a few inches of water to a simmer in a saucepan or bottom of a double boiler.

Put the sugar and zest in a large metal bowl that can fit over the pan or in the top of the boiler.

Off heat, work the sugar and zest together between your fingers until the sugar is lemony and aromatic.

Whisk in the eggs followed by the lemon juice.

Set your bowl over the water so that it's not touching or better yet, just put the double boiler on top.

Set your deep fry thermometer in the mixture (or use an instant read) and whisk mixture constantly over simmering water until the thermometer reads 180°F. This could take up to 10 minutes.

At 180°F, pull the cream from the heat and strain it into the container of a blender (or food processor); discard the zest. Let the cream rest at room temperature, stirring occasionally, until it cools to 140°F, about 10 minutes.

Turn the blender to high and, with the machine going, add about 5 pieces of butter at a time. Scrape down the sides of the container as needed while you’re incorporating the butter. Once the butter is in, keep the machine going to get an airy texture. Work in bursts if your machine tends to overheat.

Pour the cream into a container, press a piece of plastic wrap against the surface to create an airtight seal.

Chill the cream for at least 4 hours or overnight. When ready to use, whisk the cream.