Filbert Cream Ice (Crème d'Avelines)

Ingredients

• 1 pint (approximately 200g shelled weight) filberts (hazelnuts), in shell (Also sold as hazelnuts. Buy whole, unshelled if possible; shelled raw hazelnuts also work.)
• 8 yolks raw egg yolks (Use large, fresh eggs. Separate carefully — no whites should be included.)
• 1 pint (570ml) single or whipping cream (Used to make the custard base. Full-fat cream gives the best result.)
• 1 wine-glass (approximately 100ml) white rum (Silver Rays or similar white rum) (A standard wine glass is roughly 100ml. Use any good-quality white rum.)
• 1 wine-glass (approximately 100ml) noyeau syrup (Noyeau is an almond-flavoured liqueur syrup. Use a non-alcoholic almond syrup or orgeat if unavailable.)
• 4 ounces (115g) caster sugar (Fine caster sugar dissolves more easily than granulated. Modern caster sugar is identical to historical 'castor sugar'.)
• 1 teaspoon essence of vanilla (Vanilla extract works as a direct modern substitute.)
• 0.5 pint (285ml, before whipping) double (heavy) cream, whipped (Whip to soft peaks before folding in. Use double or heavy cream for best volume and stability.)

Instructions

1. 1If your filberts are still in their shells, crack and remove all the shells. Place the shelled filberts into a medium saucepan and cover completely with cold water. Set the pan over high heat and bring to a full boil. This blanching process loosens the papery brown skins on the nuts.
2. 2As soon as the water comes to a full boil, immediately drain the filberts through a colander or sieve. Rinse them under cold running water for about 30 seconds to cool them down. Working with a clean, dry kitchen cloth (a tea towel is ideal), take a small handful of filberts at a time and rub them firmly inside the cloth. The skins will slip off with the friction. Continue until all the filberts are skinned. Do not worry if a little skin remains — just remove as much as you comfortably can.
3. 3Place the peeled, still-slightly-warm filberts into a food processor or high-powered blender (the modern equivalent of a mortar and pestle). Process continuously, scraping down the sides of the bowl as needed, until the nuts form a completely smooth, fine paste with no large chunks remaining. This may take 3–5 minutes of blending. If using a mortar and pestle as in the original recipe, pound patiently in circular motions until the mixture is uniformly smooth.
4. 4Transfer the smooth filbert paste into a large, heavy-bottomed saucepan. Add the 8 egg yolks, 1 pint (570ml) of cream, 1 wine-glass (approximately 100ml) of white rum, 1 wine-glass (approximately 100ml) of noyeau syrup, and 4 ounces (115g) of caster sugar. Gently whisk or stir everything together until the sugar is dissolved and the mixture is thoroughly combined and uniform. Take care not to incorporate too much air.
5. 5Place the saucepan over a medium-low heat. Stir the mixture constantly with a wooden spoon or heatproof spatula, making sure to scrape the bottom and sides of the pan continuously so nothing scorches. Cook slowly until the custard thickens enough to coat the back of the spoon — when you draw a finger across the back of the spoon, the line should hold clearly without the custard running back together. This usually takes 10–15 minutes. Do NOT allow the mixture to boil, as this will scramble the egg yolks.
6. 6Remove the pan from the heat. Set a fine-mesh sieve (the modern equivalent of a tammy cloth) over a large, clean bowl. Pour the hot custard through the sieve, pressing any solids gently with the back of a spoon to extract as much liquid as possible. Discard any solids caught in the sieve. The strained custard should be smooth and lump-free. Allow the custard to cool slightly in the bowl.
7. 7Allow the strained custard to cool to room temperature. To speed this up, place the bowl into a larger bowl filled with ice and cold water, stirring occasionally, until the custard is cool to the touch. Once cooled to room temperature, cover the bowl with cling film and refrigerate until fully cold — at least 2 hours, or overnight for best results. The custard must be completely cold before you add the whipped cream and freeze.
8. 8Once the custard is completely cold, take it out of the refrigerator. Whip the 1/2 pint (285ml) of double cream in a chilled bowl using a hand whisk or electric mixer until it reaches soft peaks — it should hold its shape gently but not be stiff or grainy. Stir the teaspoon of vanilla essence into the cold custard. Then gently fold the whipped cream into the custard using a large metal spoon or spatula, using slow over-and-under movements to keep as much air in the cream as possible. The mixture should be smooth and airy.
9. 9If using an ice cream machine: pour the mixture into your machine and churn according to the manufacturer's instructions until thickened and frozen to a soft-serve consistency, usually 20–30 minutes. Transfer to a lidded freezer-safe container and freeze for at least 2 hours until firm. If you do not have an ice cream machine: pour the mixture into a shallow, freezer-safe container and place in the freezer. After 1 hour, remove and beat vigorously with a fork or hand mixer to break up ice crystals. Return to the freezer. Repeat this process every 30–45 minutes for 3–4 hours until the ice cream is smooth and firmly set.
10. 10Remove the ice cream from the freezer approximately 5 minutes before serving to allow it to soften slightly for easy scooping. Serve in chilled bowls or dessert glasses as an elegant dinner or dessert ice.