Step 1

Measure out the sugar. Zest lemon directly into the sugar and rub everything together for about a minute or so, until the sugar gets fragrant.

Step 2

Use a food processor to grind the basil leaves with the lemon sugar and one cup of the heavy cream, until the leaves are ground as fine as possible. Be careful not to whip the cream already. Feel free to pre-grind the basil with a bit of the milk from the recipe before adding the cream. Pour half of the mixture through a strainer into a large bowl. Add the remaining 1 cup of heavy cream.

Step 3

Heat the other half of the basil lemon puree in a saucepan along with the whole milk and salt over medium heat. In another bowl, whisk together the egg yolks. When the basil mixture is steaming, slowly pour into the egg yolks while whisking constantly. Return the mixture back into the saucepan.

Step 4

Stir the mixture constantly over medium heat with a spatula, scraping the bottom as you stir, until it is thick enough to coat the back of a spoon, about five minutes. Pour the custard through the strainer into the bowl with the cream mixture. Cool custard over an ice bath while stirring.

Step 5

Chill completely, then freeze in an ice cream machine according to the manufacturer's instructions. Let harden in the freezer for a few hours before serving.