Preheat the oven to 375°F (190°C) and lightly grease a pie dish.
Roll out puff pastry to line the dish, trimming edges. Prick the base with a fork.
Layer sliced potatoes at the bottom, followed by salmon, fennel, dill, and ricotta. Repeat layers, finishing with salmon on top.
In a bowl, whisk eggs, cream, salt, and pepper. Pour the mixture evenly over the pie filling.
Bake for 45-50 minutes until the top is golden and the filling is set.
Let cool for 10 minutes, garnish with dill and lemon slices, and serve.