Bring a large pot of water to the boil for cooking the pasta.
Heat 2 teaspoons of the oil in a large non-stick frying pan over medium-high heat. Add the eggplant and cook, turning from time to time, until browned and tender, 5 to 7 minutes. Transfer to a plate.
Reduce the heat to medium and add the remaining 2 teaspoons of oil to the frying pan. Add onion and cook, stirring often, until softened, 2 to 3 minutes. Add the garlic and chilli. Cook, stirring, until fragrant, about 30 seconds. Add the tomatoes and bring to a simmer. Add the eggplant. Simmer, uncovered, over medium-low heat until the flavours have developed and the sauce has thickened, 15 to 20 minutes. (Add a little water if the sauce thickens too quickly.) Stir in 2 tablespoons of the parsley. Season with pepper.
Meanwhile, cook the pasta in the boiling water until al dente (just tender) or according to packet directions. Drain, return to the pot and add the sauce. Toss to coat well. Sprinkle each serving with fetta, pine nuts and some of the remaining parsley (or basil).
Toast the pine nuts in a small dry frying pan over medium-low heat, stirring constantly, until golden and fragrant, 1 to 3 minutes.