Pat the chicken livers dry with kitchen paper, trim off any dark patches and cut into small chunks. Heat the oil in a large, nonstick frying pan over a high heat, add the livers and fry for 1-2 minutes each side until just browned on the outside. Transfer to a plate. Tip the mushrooms and tomatoes into the pan and fry for 6-7 minutes, stirring, until cooked and golden, then transfer to a separate plate. Bring a large pan of salted water to the boil and cook the tagliatelle according to your packet’s instructions

Meanwhile, heat the butter and Marmite in the frying pan over a medium heat. Stir in 2 tbsp of the pasta cooking water and return the livers to the pan; cook for 4 minutes or until the livers are cooked through. Drain the pasta, add to the frying pan and toss to coat in the buttery sauce. Stir in the mushrooms, chives and parsley to serve. Scatter the pistachios on top.