- Preheat your slow cooker to the highest setting and place and heat a little oil in a large frying pan over a medium-high heat.
- Brown your sausages evenly in the hot pan, then add in your red onion and cook for 5 minutes, stirring, until the onions are soft and caramelised.
- Transfer the sausages and onion into your pre-heated slow cooker and combine the sachet of Colman’s Full of Flavour Sausage Casserole Seasoning Mix with water, then pour over.
- Add in your cannellini beans, then stir, top with rosemary and cover, leaving for 2 hours to cook.
- Half an hour before your casserole is ready, start making your Yorkshire puddings. Place an 8 inch cake tin in the oven with a little vegetable oil, then preheat the oven to 200c. Whisk the eggs into the plain flour, then slowly add in the milk, whisking to a smooth batter. Pour this into the hot cake tin, about ¼ full and bake for 20 minutes, until fully risen.
- Spoon the sausage casserole into the Yorkshire Pudding bowls and serve with a dollop of Colman’s English Mustard (optional).