For the chicken, place the bread and parsley into a food processor and pulse to fine breadcrumbs. Transfer to a large bowl or shallow dish.
Place the butterflied chicken breast in between two sheets of cling film and flatten out with a meat mallet or rolling pin until half as thin. Dip into the beaten egg, then roll in the parsley breadcrumbs to coat all over. Shake off any excess breadcrumbs.
Heat the olive oil in a frying pan and fry the chicken breast for five minutes on both sides, or until golden-brown and cooked through.
For the spinach, heat the oil in a wok and add the spinach and chilli flakes, stirring gently for 2-3 minutes, or until the spinach is wilted. Season with salt and freshly ground black pepper.
For the herb pesto, place all of the pesto ingredients into a food processor and pulse until well combined.
To serve, spoon the wilted spinach onto a serving plate and top with the fried chicken. Drizzle the pesto around the edges of the plate, and spoon a dollop of the Greek-style yoghurt to the side.