Place the heavy cream in a 1-quart capacity container (I use a mason jaand set aside.Place the egg yolks in a medium bowl anchored on a damp towel and set aside.
In a medium saucepan, warm the milk, sugar and salt over a medium flame, swirling the pot occasionally until the milk is steaming and small bubbles form on the bottom of the pan, a few minutes.
When the milk is hot, dribble it into the yolks, whisking constantly. Return the mixture to a medium-low flame, and cook, stirring constantly with a heat-proof silicone spatula, scraping the sides and bottom of the pan, until the mixture begins to "stick" (form a film othe bottom of the pan, a few minutes.
Immediately remove the pot from the heat and pour the hot custard into the cold, heavy cream. Place in the fridge to chill for at least 4 hours, and up to 2 days. (If you're in a hurry, you can place the mixture in an ice water bath and stir until it is cold.)
Prepare the tarragon:
Bring a medium saucepan of water to a rolling boil. Have a medium bowl filled with ice water at the ready. Blanche the tarragon until bright green, 5-10 seconds, drain through a strainer, and plunge into the ice water. When it's cold, drain it and use your hands to squeeze all the water out.
Place the blanched, squeezed tarragon in a blender. Add about a cup of the cold ice cream base and blend on low until smooth, slowly adding the remaining ice cream base. With the motor still running, slowly pour in the olive oil. Strain the mixture through a fine-mesh sieve.
Churn the ice cream:
Return the ice cream base to the jar and place it in the freezer for half an hour to get it really cold, shaking or stirring it every 10 minutes (this will make for a smoother ice cream). Spin the ice cream in an ice cream maker until it is the consistency of a thick milkshake. Transfer the ice cream to a storage container (preferably one that has been chilled in the freezeand freeze for at least 2 hours for a scoopable consistency.
Serve scoops of ice cream with a drizzle of olive oil and a pinch of flaky sea salt, such as Maldon. The ice cream is best within a week of being made, but will keep for several months.
Inspired by Tim Nugent and based on David Lebovitz' Olive Oil Ice Cream from The Perfect Scoop.This ice cream is all about the olive oil, so use the best stuff you can afford, preferably freshly-pressed and extra-virgin.French tarragon (as opposed to the Russian variety) has the best flavor and is the stuff most commonly found at well-stocked grocery stores and farmer's markets (see photo in post, above).This ice cream is 'amusing and surprising' on its own, or drizzled with a bit of extra olive oil and flecked with a pinch of flaky sea salt; see the post above for further serving suggestions.Nutritional values are based on one of six servings.