WHISK: In a heatproof bowl with a hand mixer or the bowl of your stand mixer with a whisk attachment, combine the egg yolks and sugar until creamy and pale yellow; approximately 1-2 minutes. Whisk in the cornstarch until combined.

SIMMER: Heat the milk and cream in a 2-quart saucepan over medium heat until tiny bubbles start forming around the rim of the saucepan. Do not let the cream boil. Remove from heat. Gradually pour the hot cream in a steady stream into the egg mixture while the mixer runs until completely incorporated and smooth.

COOK: Transfer the mixture back into the saucepan and then heat over medium-low heat whisking constantly. Add the vanilla paste (don’t add extract yet.) Allow the pastry cream to cook until it thickens; about 4-5 minutes. Once thickened, remove from heat. Strain the pastry cream through a fine mesh strainer into a bowl. Then stir in the butter and add vanilla extract (if using.) Press a sheet of plastic wrap over the surface of the pastry cream and make sure there aren’t any air bubbles between the cream and the plastic. This will keep the patisserie cream from developing a skin. Bring to room temperature and refrigerate for at least 2 hours before piping. The filling can be made up to 48 hours in advance.

TARTS: Whisk the pastry cream with a hand mixer until smooth and airy. Pipe into prepared tart shells. Top with fresh berries as desired. Melt the apricot preserves in the microwave with a teaspoon of water for 15-30 seconds and brush the fruit with this using a pastry brush. I like to refrigerate the fruit tarts for 1 hour before serving, but this is optional.