Gather all your ingredients: espresso, heavy cream, sugar, egg yolks, cornstarch, vanilla extract, and salt.

Brew the coffee ahead and let it cool.

Pour the cooled espresso into a saucepan and heat over medium heat until steaming but not boiling (about 2-3 minutes).

In a separate bowl, whisk together egg yolks, sugar, cornstarch, and a pinch of salt until glossy and slightly thickened (about 2 minutes).

Slowly drizzle the hot espresso into the egg mixture, whisking continuously to temper the eggs.

Return the tempered egg mixture to the saucepan and cook over medium heat, stirring constantly until thickened (about 5-7 minutes).

Remove from heat and stir in vanilla extract.

Cover the custard with plastic wrap touching the surface to prevent a skin from forming and chill in the fridge for at least 1 hour.

In a separate mixing bowl, whip heavy cream until soft peaks form (about 3-5 minutes).

Be cautious not to overwhip.

Once chilled, gently fold the whipped cream into the custard using a spatula to maintain the airy texture.

Your filling is now ready to be piped into cakes, layered in cupcake liners, or served in dessert cups.