Pour the flour, eggs and milk with a pinch of salt in to a cuisinart. Mix until smooth. Leave mixture to sit.
Heat oven to 430.
In a baking tray, add the beef dripping until it melts.
Bring it to a boiling point in the oven.
Once the beef dripping begins to smoke in the oven (approximately 10 minutes), remove from oven and add sausages.
Quickly brown sausages on top of the stove, and when the oil is still very hot, add the batter, red onions and rosemary.
Cook it in the oven until sausage is done, making sure Yorkshire pudding mixture doesn't burn (approximately 20-25 minutes).
Serve with green beans, mashed potatoes, cabbage, peas and gravy.