• The day before you plan to churn the ice cream, place the bowl of your ice cream maker into the freezer.

Infuse the milk/cream:

• Place the cream, milk and half of the sugar into a medium-sized saucepan. Use a small, sharp knife to split the vanilla bean in half and scrape out the seeds. Add the seeds, vanilla bean halves, cinnamon sticks and grated nutmeg to the saucepan, then place over low heat.
• Stir every now and then while the sugar melts and the milk mixture heats up. Allow the mixture to come to just below the boil, then remove from the heat, cover with a lid and set aside to infuse for 30 minutes.
• After 30 minutes, remove and discard the two vanilla bean halves and the cinnamon stick.

Make the custard base:

• Remove 125ml of the infused milk mixture and set aside. Place the rest of the milk mixture back over the heat and stir every now and then while it comes back up to just below the boil.
• While this is happening, use an electric whisk to beat the egg yolks and the remaining sugar together, until the mixture is pale, thick and fluffy (the 'ribbon stage').
• Add the reserved 125ml of the milk mixture and whisk again to incorporate. This will slacken the eggs and make it easier to mix in the hot milk mixture.
• When the milk mixture has come up to temperature, add the milk to the eggs in a slow, steady stream, stirring all the time, until it has all been incorporated.
• Pour the mixture back into the saucepan through a heatproof, fine mesh sieve (to ensure the custard is smooth).
• Place the saucepan over a medium-low heat and stir frequently with a heatproof spatula as the custard thickens. Once thick (it should coat the back of a spoon, this will take about 8-10 minutes), remove from the heat.
• Pour the thickened custard into a heatproof jug and cover the surface directly with cling film, to prevent it from forming a skin. Allow to cool slightly at room temperature, then place into the fridge to chill for at least 3-4 hours (preferably overnight).
• Once the custard base is completely cold, add the bourbon/other alcohol (if using) and stir through well.

Churn the ice cream:

• Once the custard is cold and the alcohol (if using) has been added, set up your ice cream maker, as per your machine's instructions.
• With the machine running, pour the custard into the machine and allow to churn for 10-30 minutes, until thick and creamy.
• Transfer the churned ice cream to a freezer-safe container and freeze for at least 3 hours (preferably overnight) before serving. The ice cream will keep in the freezer for up to 3 months.