Add the chopped dates and dairy-free milk to a large saucepan over medium heat. Cook for 5-10 minutes or the dates are very soft. Remove the saucepan from the heat. Add the butter and stir until it has melted.
Mash the date mixture with a fork or blend with a blender or food processor. If you'd like some chunks of dates in your vegan sticky toffee pudding, only blend half of the mixture. Set aside to cool slightly.
Preheat your oven to 180°C (350°F). Using melted vegan butter or oil, generously grease around 9 pudding tins (mine were 7cm wide and 7cm tall) or a 12-cup muffin tray. Or line an 8-inch (20cm) square baking tin with parchment paper. If using pudding tins, place them on a large baking tray.
In a large mixing bowl, whisk the flour, brown sugar, baking powder, baking soda and salt until combined. Add the date mixture and mix until just combined.
Divide the batter into your pudding tins or pour into your large baking tin. If needed, smooth the top of the pudding(s).
If you're using pudding moulds, bake them for 25 minutes. If using a muffin tin, bake them for 20 minutes. If you're making a large pudding, bake for 32-37 minutes. If you use a ceramic dish, your pudding may take a few extra minutes to bake. The pudding is ready when you can insert a toothpick into the middle and it comes out clean. Remove the pudding from the oven and place the tin(s) on a cooling rack.