Preheat your oven to 375°F (190°C). Lightly grease 8 mini tart pans.
Roll out the pie crust and cut into 8 circles large enough to fit into the tart pans. Press gently into each pan and trim any excess.
Heat olive oil in a skillet over medium heat. Reserve 8 slices of leeks; add the rest to the skillet and cook for 5 to 7 minutes, until soft. Stir in the garlic and cook for another 30 seconds. Remove from heat and let cool slightly.
In a bowl, mix together ricotta, Parmesan, egg, salt, and pepper. Stir in the cooked leek mixture.
Spoon the filling evenly into each tart shell.
Arrange thin slices of zucchini on top of each tart, slightly overlapping, along with a slice of leek.
Bake for 25 to 30 minutes, or until the crust is golden and the filling is set.
Let cool for a few minutes before removing from the pans. Serve warm or at room temperature with fresh dill.