In a sauce pan, put your desired amount of pasta onto cook with some water and a pinch of salt. This should take around 10-15 minutes.
Meanwhile, chop up the leek and the mushroom into thin slices. Place them in a frying pan with a small amount of olive oil, butter or your chosen frying oil. Stir them often, they should take around 6-8 minutes before they are ready for the next step.
When the mushroom and leek has softened and shrunk down a little, crumble up your stock cube finely and sprinkle it over the leek and mushroom. Immediately afterwards, add the cream and stir together. Leave this to simmer for around 3 minutes, stirring occasionally. When both the pasta and the sauce are finished, serve the pasta on a plate then pour the sauce over it. Sprinkle with black pepper if desired.
This recipe is great as it can be improvised upon with the addition of chicken, Quorn, bacon or pretty much anything else.