Cook the spaghetti in a pan of boiling water, following pack instructions.
Meanwhile, fry the bacon pieces over a medium heat for 5 minutes until browned and crispy. Remove from the pan and set aside on a plate.
Fry the sliced mushrooms with the onion and garlic for 3-4 minutes in the oil left in the pan from the bacon.
Return the bacon to the pan and add the spinach leaves, egg yolk, cream and milk, and stir well until heated through.
Remove from the heat, add the cooked spaghetti and stir through to serve.
Raw egg advice: Some recipes have raw eggs in them including Hollandaise sauce, homemade mayonnaise and a variety of ice creams (some of which involve cooking and some that don’t.) If you're pregnant, elderly, very young (babies/toddlers) or are already unwell it's recommended that you don't consume raw eggs or uncooked foods containing raw eggs.