Cook the pasta in a large pan of boiling water, as per the packet instructions.

When the pasta is almost cooked, scoop out a cup of the pasta cooking water and keep aside.

Whilst the pasta is cooking, place the butter into a pan and sauté the onion.
Once soft, add the pate and stir until it is melted.

Add enough of the pasta coking water to make a coating sauce.

Toss the pasta in the pate sauce and serve immediately.