Heat the vegetable oil in a large pan over a medium heat.
Add the mince and cook until golden-brown all over. Remove the mince from the pan with a slotted spoon and set aside.
Add the chicken livers to the same pan and cook until browned all over. Remove the livers from the pan and chop into bite-sized pieces and set aside.
Add the onion to the pan and fry for 4-5 minutes, to soften and colour.
Add the garlic, red and green peppers and mushrooms and fry for 5-6 minutes, or until softened and lightly coloured.
Add the cooked mince, the cooked livers, the tomato purée and bay leaves and continue to cook for eight minutes.
Add the wine and tomatoes and bring to the boil. Reduce the heat and simmer for 30-45 minutes.
Season, to taste, with salt and freshly ground white pepper.
Add the thyme, parsley and oregano and stir well to combine.
To serve, place equal portions of cooked spaghetti into four serving bowls. Spoon equal amounts of Bolognese sauce over each portion and sprinkle with finely grated parmesan.
