Crush the graham crackers into fine crumbs.

Pulse them in a food processor to speed things up.

Combine the crumbs and melted butter in a mixing bowl.

Press the crumb mixture firmly over the bottom and up the sides of a springform pan or cake ring.

Chill for at least 15 minutes, until the crust is set and firm.

Heat the oat milk in a saucepan.

Whisk the egg yolks, sugar, vanilla, and cornstarch together in a bowl.

Whisk one third of the hot oat milk into the egg mixture until the cornstarch and sugar are fully dissolved.

Pour the mixture back into the remaining hot milk and cook over medium-low heat, stirring constantly, until thickened.

Remove from the heat.

Add the pistachio paste and cold vegan butter.

Blend with an immersion blender until smooth.

Transfer to a clean, dry container.

Cover with plastic wrap.

Chill for at least 1 hour, preferably overnight.

Preheat the oven to 180 °C.

Whisk the chilled pistachio pastry cream until loosened.

Pour it over the chilled crumb crust.

Tap the pan a few times to release any air bubbles.

Smooth the top with a large spoon or offset spatula.

Bake for 40 to 50 minutes, until the top is lightly caramelized.

Check that the center still has a slight wobble.

Let cool off the baking sheet, then refrigerate for at least 4 hours, preferably overnight.

Brush the top with warm clear fruit glaze just before serving.