For the gremolata: In a bowl, combine the parsley, spinach, chiles, garlic, lemon zest and juice, olive oil and salt. Mix well. Set aside.
For the chicken livers: Heat the butter and olive oil over medium-high heat in a heavy-based pan. Fry the livers for 3 to 4 minutes; remove from the pan with a slotted spoon and drain on paper towels.
Reduce the heat to medium and add the onions, bacon, mushrooms, chiles, paprika and thyme; cook until the onions have softened, 8 to 10 minutes, adding the garlic for the last minute.
Add the red wine, tomato paste, tomatoes, brown sugar, cream, pepper, salt and parsley; simmer for 5 minutes. Add the chicken livers back to the pan and simmer for a further 5 minutes. Serve with the gremolata.