Wonder if I could borrow this lot?
Saute a chopped onion in olive oil, add sliced mushrooms and fry until just done. Season.
Meanwhile, cook some tagliatelle, drain..leaving some of the cooking water.
To the onion and mushrooms (when they are cooked) add a couple of spoonfuls of pesto sauce. Mix and add to the pasta...slosh in some of the water to the veg and pesto mix if it needs loosening up. It can be a bit claggy sometimes.
Serve, Sprinkle on grated cheese if desired... Really yummy...and cheap!