Method

Infuse the Milk

In a medium saucepan, combine the milk and lemon zest. Gently heat over low-medium heat until it’s warm but not boiling. Allow the milk to steep for about 5 minutes to infuse the lemon flavor.

Prepare the Egg Mixture

In a mixing bowl, whisk together the egg yolks and sugar until pale and creamy. Add the cornstarch and whisk until smooth.

Temper the Eggs

Slowly pour a ladle of the warm milk into the egg mixture, whisking constantly to prevent curdling. Repeat with another ladle, then pour the tempered mixture back into the saucepan with the remaining milk.

Cook the Custard

Cook the mixture over medium heat, stirring constantly with a whisk to prevent lumps. The custard will begin to thicken after about 5 minutes. Once it reaches a smooth and thick consistency, remove it from the heat.

Flavor and Cool

Stir in the vanilla extract and optional butter until fully incorporated. Pour the custard into a clean bowl and cover the surface with cling film (pressing it directly onto the custard to prevent a skin from forming). Let it cool to room temperature, then refrigerate for at least 30 minutes before using.

Variations and Tips

Variations:

Orange Custard: Substitute lemon zest with orange zest for a sweeter citrus flavor.

Alcohol-Infused: Add a splash of limoncello for an adult twist.

Dairy-Free: Use almond milk or oat milk and a plant-based butter substitute.

Tips:

Constant stirring during cooking ensures a silky, lump-free texture.

If you prefer an ultra-smooth custard, pass it through a fine mesh strainer before cooling.

For a richer custard, substitute half the milk with heavy cream.

Substitutions for Dietary Needs:

Use a sugar substitute like erythritol for a lower-sugar version.

Replace cornstarch with potato starch for a gluten-free alternative.