Heat the Milk and Cream:

In a medium saucepan, combine the whole milk, heavy cream, and instant coffee granules or espresso powder. Heat the mixture over medium heat until it begins to steam, but do not let it boil. Stir occasionally to help dissolve the coffee granules.

Prepare the Egg Yolks:

In a separate mixing bowl, whisk together the egg yolks and sugar until the mixture is pale and thick.

Temper the Eggs:

Slowly pour a small amount of the hot milk mixture into the egg yolk mixture, whisking constantly to temper the eggs and prevent them from scrambling.

Gradually add the tempered egg mixture back into the saucepan with the remaining milk mixture, whisking continuously.

Cook the Custard:

Cook the mixture over medium heat, stirring constantly, until it thickens enough to coat the back of a spoon, about 5-7 minutes. Do not let it boil.

Add Vanilla and Chill:

Remove the saucepan from the heat and stir in the vanilla extract (and coffee liqueur, if using). Pour the custard through a fine mesh strainer into a clean mixing bowl to remove any cooked egg bits.

Cover the bowl with plastic wrap, pressing it directly onto the surface of the custard to prevent a skin from forming. Refrigerate for at least 2 hours, or until completely chilled.

Churn the Ice Cream:

Once the custard is chilled, pour it into your ice cream maker and churn according to the manufacturer’s instructions, usually about 20-25 minutes.

Add the Chocolate Chips:

During the last few minutes of churning, add the chocolate chips or chopped chocolate to the ice cream maker, allowing them to mix in evenly.

Freeze the Ice Cream:

Transfer the churned ice cream to a freezer-safe container. Cover and freeze for at least 4 hours, or until the ice cream is firm.