Heat the olive oil in the saute pan over a low heat, then add in the onion and fry for about 5 minutes, until softened but not coloured. Turn the heat up and add in the mince, and continue to cook, stirring occasionally until browned. Add the garlic, mushrooms and carrot, and cook for another couple of minutes until soft. Add in the tinned tomatoes, the stockpot, the puree and the worcestershire sauce. Fill the tin with water to rinse out all of the tomato and add that to the pan. Season with a little salt and pepper, then simmer for 15-20 minutes until the sauce has thickened. Keep warm.
Fill the large saucepan two thirds full with cold water, cover and bring to the boil over a high heat. Add the spaghetti and cook without the cover according to the packet instructions, usually 10-12 minutes for dried. Drain and serve immediately.
Divide the pasta between four dishes, then spoon over the bolognese sauce. Sprinkle with the basil for an extra zing.