1 Preheat your oven to 180°C. Roll out the shortcrust pastry to roughly 3mm thick. Carefully lift it into a 23cm tart tin and gently press it into the edges. Trim off any excess pastry and prick the base all over with a fork.
2 Line the pastry case with parchment paper and fill it with baking beans or rice. Blind bake the pastry for 15 minutes, then remove the parchment and beans and return the pastry case to the oven for another 5 minutes to allow the base to dry out. Brush the pastry base with 1 egg yolk then place back in the oven for another 1 minute to set then remove from the oven.
3 In a bowl, whisk together the milk, cream, eggs, and egg yolk, and chopped chives until well combined. Season the mixture with salt and black pepper.
4 In the cooled pastry base add the cooked spinach, blanched and sliced asparagus, and sliced pickled pears, and caramelised onions to the egg mixture and stir to combine. Slice the brie into thin slices and scatter them evenly over the base of the pastry case. Pour the egg mixture over the brie and spread it out evenly.
5 Bake the quiche for approximately 30-40 minutes, or until the filling is set and golden brown on top.
6 Once the quiche is baked, remove it from the oven and allow it to cool for a few minutes before slicing and serving.