In a large bowl whisk the muscovado and caster sugar into the oil. Then whisk in the oat milk and vanilla.
In a second bowl sift in the flour, baking powder, bicarbonate of soda, salt and cinnamon.
Stir through the chocolate chips and dark chocolate chunks.
Fold the wet mixture into the dry ingredients just until all the flour has been incorporated.
Cover the bowl and chill the cookie mixture in the fridge for 30 minutes.
Preheat the oven to 200°C/ fan 180°C / Gas 6. Remove the bowl from the fridge and place in the freezer for 10 minutes. Line 2 baking trays with baking parchment.
Remove the cookie dough from the freezer. Form the dough mixture into 16 balls and place on the 2 baking trays. There is no need to flatten the cookie balls as they will spread out once in the oven.
Bake in the oven for 10 minutes. The cookie edges should have lightly browned.
Remove the cookies from the oven and leave to cool and firm up for 5 minutes on the baking tray.
Transfer to a wire rack and leave to cool completely.