Add all the ingredients to the Thermomix bowl. Mix for 20 seconds / speed 4. Transfer to a jug, cover and set aside for at least 30 minutes to an hour. Refrigerate if leaving for longer than an hour.
Increase oven temperature to 220 C / 430 F.
Pour ½ teaspoon of oil into the bottom of each hole of the muffin tin. Place in the hot oven to heat for 15 minutes.
Carefully remove the muffin tray from the oven and pour in the batter to ¾ fill each muffin compartment.
Immediately return the tray to the hot oven and cook for 20-25 minutes with the door firmly closed throughout until the Yorkshire puddings have puffed up and turned golden brown. Serve immediately.
