Preheat the oven to 190°C, fan 170°C, gas 5. Cook the asparagus in a large pan of boiling water for 3-6 mins, until just tender. Drain and set aside.
On a lightly floured board, roll out the pastry and use to line a 20 x 30cm shallow baking tin or Swiss roll tin, trimming away any excess pastry. Prick the base all over with a fork and bake for 5 mins.
Heat the olive oil in a frying pan and gently cook the spring onions for a few mins until tender. Tip into a bowl to cool slightly, then add the crème fraîche, eggs, Parmesan and chives, and mix well.
Spoon the egg and crème fraîche mixture into the pastry base, then arrange the asparagus spears on top, pressing them gently into the mixture. Sprinkle over the toasted pine nuts.
Bake in the oven for 30 mins or until the top is puffed and golden and the pastry is cooked through. Cut the asparagus tart into slices and serve with the spinach, watercress and rocket salad.