1. In a medium saucepan, warm the lemon verbena leaves with the milk, 1/2 cup (125ml) of the cream, the sugar, and a pinch of salt.
2. Once warm, remove from heat, cover, and let steep for one hour.
3. To make the ice cream custard, pour the remaining cream into a large bowl set in a larger bowl of ice water, and put a mesh strainer on top.
4. Use a strainer or slotted spoon to skim the lemon verbena from the cream & milk mixture and squeeze the leaves to extract as much liquid as possible back into the saucepan, then discard them. Rewarm the lemon verbena-infused cream & milk, then
5. In a separate bowl, whisk the eggs together in a small bowl and slowly pour in the warm infusion, whisking constantly.
6. Scrape the warmed egg yolks back into the saucepan and cook, stirring continuously with a heatproof spatula, until the custard leaves a trail on the spatula when you drag your finger across it. (If using a thermometer, it should read about 175ºF, or 79ºC.)
7. Immediately strain the custard into the bowl of cream. Stir until cool.
8. Chill thoroughly, then freeze in your ice cream maker according to the manufacturer’s instructions. When done, crumble a dried verbena leaf in the ice cream, or finely-chop a fresh leaf and stir that in.