Begin by rolling out the dough between two cereal packet liners until you achieve a circle approximately 23 cm in diameter.
Chill the rolled pastry for about 30 minutes.
Once chilled, carefully peel off the top layer of plastic and brush the tin with lining paste.
Place the pastry, pastry-side down, into the tin, ensuring it fits snugly into all the ridges, corners, and edges.
If the pastry feels brittle, allow it to sit at room temperature for a few minutes; if it sticks, return it to the fridge for another five minutes.
Remove the plastic and use a fork to prick the base of the pastry to prevent it from puffing up.
Line the pastry with baking paper and fill it with baking beans or a cotton cloth, then bake it blind for 15 minutes.
After 15 minutes, take out the paper and beans; if the base still appears waxy, bake for an additional 5 minutes until it is dry and fully cooked.
Brush the baked crust with egg white to create a waterproof seal and bake for an additional 2 to 3 minutes.
While the crust is still warm, use a serrated knife and a clean tea towel to trim away any excess pastry from the edges.
Blend the cheese, onion, and chives together, then pour the filling into the prepared crust.
Bake the quiche until the filling is set and the top is lightly golden.
