1. Let the butter soften to room temperature to make it easier to work with.
2. Combine the flour and salt. Add the butter to the flour and mix until combined – it will look like breadcrumbs.
3. Now add an egg and mix until the dough comes together. Depending on the size of the egg, it may be necessary to add a little water. Mix until the dough sticks together, but don’t knead it.
4. Shape the dough into a ball, cover with cling film and place in the fridge. Refrigerate for at least one hour until it is firm enough to work with.
5. Now roll out the dough to a thickness of about ½cm. Cover a greased pie dish and bake for 10 minutes at 180°C. If possible, blind bake the crust by covering it with aluminium foil and then filling with dried beans or similar to keep it from puffing up.
6. Prepare the filling, while the dough is baking -whisk the eggs with the crème fraîche and season with salt, pepper and thyme.
7. Slice the onions and sauté in a frying pan over high heat with a little oil. You want the sliced surface of the onions to caramelise.
8. Pour the egg mixture into the pie shell, then add the caramelised onions and top with slices of Castello® Double Cream Brie.
9. Bake the pie for an additional 25-30 minutes at 180°C until the filling has set and is slightly golden on top.
10. Serve hot, warm or cold.