In a mixing bowl, combine flour, salt, and herbs. Add cold butter and mix until crumbly. Stir in ice water until dough forms.

Wrap the dough in plastic wrap and refrigerate for at least 30 minutes.

In a skillet, sauté onions over medium heat until caramelized, about 20 minutes.

Add thyme, black pepper, and cream to the onions, stirring to combine.

Preheat the oven to 375°F (190°C). Roll out the dough on a floured surface.

Place the rolled dough on a baking sheet, fill with the onion mixture, and sprinkle with gruyere cheese.

Fold the edges of the dough over the filling and bake for 25-30 minutes until golden brown.