In a bowl mix the sausage meat together well with the breadcrumbs, chopped sage, black pepper and the beaten egg. Form the mixture into little meatballs.
Heat a large frying pan and add a good splash of oil, fry the meatballs until brown all over. Cook gently for a further 5 minutes and remove, keep warm. Fry the bacon for a couple of minutes, add the mushrooms and sauté for a further 2 minutes, add the garlic and remove from the heat.
Meanwhile, bring a large pan of salted water to the boil, add the spaghetti, stir well and cook for 10 – 12 minutes or until al dente.
Mix together the egg yolks, cream and half of the mature Cheddar cheese, lemon zest and parsley. When the pasta is cooked, drain, reserving a little of the cooking water and immediately toss it with the egg mixture, place back in the pasta pan and then add the meatball mixture. This should be enough heat to cook the egg mixture without scrambling it, if the mixture is a little sticky add some of the reserved cooking liquor, to loosen the mixture. Mix together. Sprinkle with the rest of the cheese.
Eat with green salad and chunky bread and crispy chards of streaky bacon.