In a medium saucepan, whisk together the sugar, cocoa powder, cornstarch, and salt until combined. n2. Gradually add the plant-based milk, whisking to ensure there are no lumps. n3. Heat the mixture over medium heat, whisking constantly until it comes to a boil. Let it boil for about 1 minute until thickened. n4. Remove from heat and stir in the vegan butter and vanilla extract until smooth. n5. Divide the pudding into serving bowls and refrigerate for at least 2 hours to set. Serve chilled, optionally topped with vegan whipped cream or chocolate shavings.