Separate the egg yolks from the whites (save the whites for another recipe).

Measure out all your ingredients to keep things smooth.

In a medium saucepan, combine milk and passion fruit puree.

Heat over medium heat until it’s warm but not boiling—just enough to release that dreamy aroma.

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

Whisk continuously to temper the eggs as you slowly add half of the warm milk mixture into the egg yolk mixture.

Return the tempered mixture to the saucepan.

Cook over medium heat, whisking continuously, until the mixture thickens (about 5-7 minutes).

Once it starts bubbling, cook for one more minute to ensure the cornstarch is activated.

Remove from heat and stir in butter until melted and glossy.

Pour the filling into a bowl, cover with plastic wrap (press it directly onto the surface to prevent a skin), and let it cool completely before using.