Heat the air fryer on 160 degrees for 2 minutes. Mix the oil, yoghurt, egg and milk in a large bowl. Then, fold in the sugar, flour and bicarbonate of soda and mix well. Fold in the blueberries.
Spoon the mixture into silicone cases, 3/4 full. You should be able to make 6-8 muffins, bake in batches.
Place the muffin cases in the air fryer and cook for 12-15 minutes until the muffins are golden brown and a skewer comes out clean from the center.
Whisk together the egg, yoghurt, milk, oil and vanilla. Stir through the caster sugar and mix until combined.
Sift in the flour and cocoa powder, then add the salt and most of the chocolate chips. Stir until just combined, with no floury streaks.
Arrange the cake cases and scoop batter evenly into each case. Sprinkle the reserved chocolate chips on top.
When preheated, remove the basket from the airfryer and put the cake cases into it. Arrange them close together, just touching.
Bake for 12-15 minutes until well-risen and the tops of the muffins spring back when pressed. Lift out of the airfryer and allow to cool on a wire rack for 15 minutes before serving.
