On medium heat, sauté the leeks with the olive oil, right before the leeks are ready, add the rest of the ingredients (except cheese, cream & eggs) and stir gently.
Mix cheese, eggs and cream with a salt and pepper. Keep aside
Lay the puff pastry in a tart dish
With the help of a fork make little holes on the base of the puff pastry but not the sides.
When the filling is cooler, fill the tart dish and pour the cream & egg mixer evenly.
Bake for 35 mins
Remove the tart from the oven and let it stay for 10 minutes before cutting a piece.
Tart, as every tart, can have whatever filling you desire. If you want to add or replace ingredients, go ahead and do it! There is nothing more pleasurable than tasting something you made with your own creativity. If you are new to cooking, this tart is a great start since it has a readymade base, and the filling is fairly easy to make, with ingredients that you can find in any super market or at the local market.