Brew your coffee.
Slowly pour pre-heated whole milk into the coffee and set it aside.
Mix the milk and coffee liquid with sugar and heavy cream in a medium non-stick saucepan and heat it on medium heat. Keep whisking until thoroughly combined.
Turn off the heat when the mixture comes to a simmer.
In a separate bowl, whisk the egg yolks until combined, and gradually add the hot milk mixture before putting it back into the saucepan.
Keep whisking the mixture over low heat until it thickens.
Turn off the heat, transfer the mixture to a glass bowl, let cool, and cover with plastic wrap.
Put the custard into the fridge to chill for at least four hours before taking it out and putting it into the ice cream machine you have at home.
Transfer the ice cream to a clean glass container and chill overnight to harden slightly.