Prepare your ice cream machine the day before, by freezing your bowl/canister for 24 hours
Prepare a large bowl (or sink) with ice. We will use this to stop the custard from cooking, by quickly reducing the temperature of the ice cream mixture.
In a medium saucepan over medium heat, heat the milk, cream and vanilla bean. Stir occasionally, until it just comes to a boil, then remove from heat
Meanwhile, use a balloon whisk to whisk the egg yolks and sugar until pale and creamy
Tempering the eggs: continue whisking the egg and sugar, while slowly adding ⅓ of the hot milk mixture. Whisk until fully combined, then slowly add another ⅓
Pour the mixture back into the saucepan containing the last ⅓ of milk mixture (wipe out the bowl to use later)
With the saucepan over low heat, use a spatula to stir the mixture constantly until thickened. It should be thick enough to coat the back of your spatula
Place a fine mesh sieve over your cleaned bowl, then pour the mixture into the sieve, scraping the mixture through. Discard the vanilla bean
Stir through the vanilla extract
Place the bowl into your ice bath, being careful not to let any ice into the mixture. You can add a little water to the ice bath if needed
Whisk the ice cream until the mixture has cooled to room temperature, then cover with plastic wrap and chill in the refrigerator overnight.
The next day, churn the ice cream in your machine, according to manufacturer's instructions. Mine takes about 20 minutes to thicken
Eat as a soft serve straight away, or freeze for 2 hours