1 cup sugar
Zest of 3 lemons finely chopped
4 large eggs
¾ cup freshly squeezed lemon juice
2 ½ sticks butter cut into tablespoon size pieces at room temperature
Bring a pan of water to a simmer. Choose a metal bowl that fits over the pan of water so that the bottom does not touch the water. In the metal bowl off the heat rub the zest into the sugar until it is very fragrant and moist. Whisk in the eggs then the lemon juice.
Fit the bowl into the pan of simmering water. Cook whisking until the cream thickens and reaches 180° on an instant-read thermometer. Remove the cream from the heat and pour through a strainer into the bowl of an electric mixer fitted with the paddle attachment. Let the cream sit at room temperature until it cools to 140°.
The butter must be at room temperature or the cream may separate. With the mixer on medium high speed (6) beat the cream while adding pieces of butter a few at a time. When the butter has all been incorporated, continue mixing for another minute.
Pack air tight and refrigerate until ready to use.
Use lemon cream in a lemon tart or to fill macarons.