Bring a medium saucepan of water to the boil and set aside a bowl of ice-cold water. Put the kale and spinach in the boiling water and cook for 2-3 mins until softened. Remove with a slotted spoon and lower into the cold water. Drain, then squeeze out the excess water.
Tip the greens into a food processor with the garlic, lemon juice and zest, basil, pine nuts, parmesan and olive oil, then blitz until smooth. Season lightly.
Tip the pesto into a saucepan with the chicken, peas, crème fraîche and stock, and bring to the boil. Tip in the gnocchi and cook for 3-4 mins until cooked through. Scatter over the extra basil leaves and grate over some parmesan to serve.