• Put pasta on to cook, as per packet instructions.
• Make a roux (a paste, warmed in a saucepan) with the oil and flour. Add 300ml stock in about 4 goes.
• Between each addition of stock stir the mixture until all the liquid incorporates into the flour and oil.
• (If you lift the pan off the heat and beat hard with a wooden spoon after the liquid is incorporated your sauce will be beautifully glossy).
• By the time all the liquid is added you should have a sauce which will coat the back of a spoon. If not add more water or stock.
• Stir in the seasonings.
• Fry finely sliced mushrooms and onion. Add to the sauce and season sauce with pepper and salt.
• Stir sauce into cooked pasta.
• Put saucy pasta in baking dish. Cook in the oven at 180 until there are nice brown crunchy bits on the top.
• Serve with the peas

Method 2- For days when you need a quick supper and less washing up

• Cook pasta as above, and fry the onion and mushrooms. Mix the flour, oil, chilli salt and pepper and garlic, whisking with a fork to remove any lumps.
• Add to the onions and mushrooms, then stir the stock in in 4 goes, stirring quickly to avoid lumps.
• When the pasta is cooked, drain it and stir the sauce through the pasta until fully coated in the garlicky mushroom sauce.
• Eat straight away.