First prepare the dough. To do this, knead the flour with the butter, salt and water until a smooth dough. If the dough is too dry, you can add a little more water. Chill the dough for 30 to 60 minutes and let it rest.
Preheat the oven to 200 °C. After resting, roll out the dough and place it in a buttered tart pan.
Trim off any excess edges, prick the dough with a fork and top with baking paper and dried beans.
Bake for 15 minutes, then remove the beans and bake for another 10 to 15 minutes until golden brown.
For the filling, whisk eggs and creme fraiche with a pinch of salt. Top the tart base with slices of goat cheese and pour the egg mixture over the top.
Sprinkle the tart with the grated Gruyère and the chives and bake in the oven at about 180 °C for another 20 minutes until the top is golden brown.
The tart is best served with a light leaf salad.