Pre-heat the oven to 200 C/ 180C fan/ gas mark 6 and line a baking tray with baking parchment. Finely chop the red onion and garlic cloves, then heat a small amount of olive oil in a frying and fry over a medium heat until softened. Pour the onions and garlic into a large bowl.
Add the sausage meat to the bowl with 1 tbsp of the marmite and season with black pepper. Marmite is very salty, so you shouldn’t need to add any extra salt. Mash everything together using a fork or squeeze together using your hands. Stir in the cheese.
Lightly flour a work surface and roll out the pastry into a large rectangle, about 35x20cm, and slice in half lengthways to create two long rectangles. Spread the
remaining marmite onto one half of each piece of pastry longways, leaving a 1cm gap at the edges.
Divide the sausage meat mixture in two and roll on a floured surface into two long sausage shapes. Make sure they are of an even thickness so the sausage rolls are the same size.
Place one of the sausage filling rolls onto the pastry strip, making sure it is directly on the top of the marmite. Brush the exposed pastry with a little beaten egg, then fold the top half over the sausage and use a fork to crimp the edge closed. Repeat with the second pastry strip and sausage filling, then arrange the long rolls in a ring shape.
Place the rolls onto a baking tray, then brush the tops of the sausage ring with the remaining beaten egg. Make several cuts around the edge of the ring, then score the top of the pastry and sprinkle with poppy seeds. Bake for 40-45 mins, or until golden brown and cooked through. Some of the cheese marmite might have oozed out, but this adds to their rustic charm. Eat warm, or cool completely and enjoy as an on the go snack!