How to Make It
In a medium saucepan, combine 3 3/4 cups of the heavy cream with the fresh and ground ginger and bring to a simmer. Cover and let cool, then refrigerate overnight.
Set a fine mesh sieve in a large bowl; set the bowl in a larger bowl of ice water. In a large saucepan, combine the lemon juice, butter and the remaining 1/4 cup of heavy cream; bring just to a simmer. In a medium bowl, whisk the whole eggs with the egg yolks and sugar until smooth. Gradually whisk in half of the hot lemon mixture; whisk the mixture into the saucepan. Cook the curd over moderate heat, stirring constantly with a wooden spoon, until thickened and an instant-read thermometer inserted in it registers 175°, about 5 minutes. Whisk in the salt and vanilla. Strain the lemon curd into the prepared bowl and let cool completely. Rinse and dry the strainer
Strain the ginger cream into another large bowl. Using an electric mixer, beat the ginger cream at high speed until firm. Fold the whipped ginger cream into the lemon curd. Spoon into glasses. Garnish with the candied ginger and refrigerate until ready to serve.