Preheat oven to 200 degrees C fan (adjust for conventional oven) and put some beef dripping into 2 Yorkshire pudding tins. Put the tins into the oven until the dripping is smoking.
STEP 2
Sift mustard powder and flour into a bowl and crack in 4 eggs into a well in the centre. Using a balloon whisk, bring together the eggs and the flour mix until smooth.
STEP 3
Gradually whisk in the milk (should be quite runny - slightly thicker than single cream).
STEP 4
Pour into the tins (the batter should sizzle) and cook for 20-25mins depending on how well done you like them.
STEP 5
You can serve immediately or you can freeze them for up to a month once cooled (just reheat in a hot oven for 5-10mins)