1. Preheat the oven to 220°C (425°F).
2. In a pan, heat the salmon but do not fully cook it.
3. Meanwhile, cook the potatoes, unroll the pastry and place it in your pie dish with the parchment paper.
4. Crumble the salmon into the pastry, then once cooked, do the same for the potatoes and place them on top of the salmon.
5. Take a large bowl, crack 3 eggs.
6. Beat them, add the milk and seasonings.
7. Pour this mixture over the salmon and potatoes.
8. Slice the tomatoes and arrange them on top of the potatoes.
9. Finally, sprinkle a generous layer of gruyère cheese.
10. Place in the oven and bake for approximately 45 minutes.
11. Enjoy your meal!!