Heat the Milk
In a medium saucepan, pour the milk and heat it gently over medium heat. If you're using a vanilla bean, scrape the seeds into the milk, then toss in the pod as well. Add the lemon zest now if you're using it. Heat until the milk is just about to simmer, then remove it from the heat.
Whisk the Egg Yolks and Sugar
In a mixing bowl, whisk the egg yolks and sugar together until they become pale and creamy. This process will take about 2-3 minutes. It's important to beat it well so the cream becomes silky smooth.
Incorporate the Cornstarch
Sift the cornstarch into the egg and sugar mixture, whisking continuously until it's fully incorporated. This step ensures that your pastry cream will thicken properly without any lumps.
Temper the Eggs
Now, slowly pour about half of the warm milk into the egg mixture, whisking constantly to prevent the eggs from scrambling. Once it's well-mixed, pour everything back into the saucepan with the remaining milk.
Cook the Cream
Return the saucepan to medium heat. Keep whisking constantly as the mixture heats up. It will start to thicken after about 3-5 minutes. Once it reaches the consistency of thick pudding, remove it from the heat.
Add Vanilla Extract
If you didn’t use a vanilla bean earlier, now’s the time to stir in the vanilla extract. Mix well to distribute that delicious vanilla flavor.
Strain for Extra Smoothness (Optional)
For an ultra-smooth texture, pass the crema pasticcera through a fine mesh strainer into a bowl. This step isn’t necessary but can remove any accidental lumps.
Cool and Set
Cover the pastry cream with plastic wrap, ensuring the wrap touches the surface of the cream. This prevents a skin from forming. Let it cool to room temperature before using, or refrigerate for later use.
Variations:
Dairy-Free: Substitute whole milk with almond, soy, or coconut milk. Just make sure to choose one with a neutral flavor.
Gluten-Free: Cornstarch is already gluten-free, but you can swap it with rice flour or a gluten-free flour blend.
Lemon or Orange Crema: Add extra lemon or orange zest for a citrusy twist.
Chocolate Crema: Stir in 100g of melted dark chocolate at the end of cooking for a rich, decadent version.