Place the cornflour in a saucepan and add about 4 Tablespoons of the milk, stir to form a smooth paste then gradually whisk in the rest of the milk.
40 g (5 Tablespoons) cornflour (cornstarch), 650 g (2 +¾ cups) soya or oat milk
Whisk in the cocoa powder, sugar, espresso powder (if using), vanilla extract and salt. The cocoa powder may not fully combine, this is fine as it will dissolve once the mixture heats up.
35 g (⅓ cup) cocoa powder, 100 g (½ cup) light brown soft sugar, 1 teaspoon instant espresso powder or instant coffee granules, 2 teaspoons vanilla extract, ¼ teaspoon table salt
Place the pan over a medium heat and stir constantly with a balloon whisk until the mixture comes up to a simmer and thickens.
Remove from the heat and whisk in the butter. Stir for a minute or two to cool it down slightly, then add the chopped chocolate and stir until melted and smooth.
45 g (3 Tablespoons) vegan block butter, 185 g (6 ½ oz) 60-75% dark chocolate
Use a spatula to scrape the mixture through a fine mesh sieve to ensure that it is free from lumps.
Pour the chocolate filling into the cooled pie crust and spread it level. Cover with plastic wrap or baking paper directly on the surface to prevent a skin from forming then refrigerate for at least 4 hours, ideally overnight, until set.
When you are ready to serve the pie, place the whipping cream, brown sugar and vanilla in a large bowl and whisk with an electric mixer until it forms stiff peaks.
250 ml (1 cup) vegan whipping cream, 1 Tablespoon light brown soft sugar, ½ teaspoon vanilla extract or vanilla bean paste
Spoon the whipped cream on top of the pie and top with chocolate curls or shavings if you like.
chocolate curls or shavings