1. Preheat the oven to 220ÂºC/425ÂºF/Gas Mark 7, 15 minutes before baking. Remove any skin and sinews from the turkey thigh meat and cut into small pieces. Reserve.
2. Place the pastry sheet on a chopping board or work surface and cut into 4 equal oblongs and place on 2 lightly oiled baking sheets. With a sharp knife mark out an oblong on each piece of pastry about 5mm/1/4 inch from the edges, taking care not to cut right through. Prick the bases all over lightly with a fork then spread each with pesto and reserve.
3. Heat the oil in a frying pan and gently sautÃ© the leeks for 5-8 minutes or until softened then add the diced turkey thigh meat and mix together. Arrange over the pesto in the pastry cases with the cherry tomatoes. Crumble the cheese and scatter over the top. Brush the edges with a little beaten egg.
4. Bake in the pre-heated oven for 15-20 minutes or until the pastry is golden and the cheese has melted. Grind over a little black pepper to taste, garnish with the basil leaves and serve.