Preheat oven to 350 degrees.
Roll out pie crust and drape over a pie dish so that it covers the bottom and sides completely.
Find a skillet with a tight fitting cover. With the skillet uncovered, heat the skillet over medium heat for a few minutes, then add the olive oil. Add the onion, salt and pepper and saute for 2-3 minutes until onion is translucent. Add the garlic and broccoli and saute for 2-3 minutes. Add water, cover the skillet with the lid and reduce heat to medium low, allowing broccoli to steam for an additional 2-3 minutes until the broccoli is bright green but still crunchy. Remove the skillet from heat and drain the broccoli in a colander. Set the broccoli aside to cool.
In a medium bowl, add milk and eggs and whisk together until just incorporated (don't overbeat the eggs or you'll get tons of froth).
Layer the broccoli evenly through the pie dish. Sprinkle the Gruyere on top, then add the milk and egg mixture. Top with the Parmesan.
Trim the edges of the pie crust with a sharp paring knife to remove the excess pastry dough and then crimp the edges with your fingers.
Slide the pie dish carefully into the oven and bake for 30-40 minutes until the top is browned and the egg custard is puffed and golden. Let cool on a wire rack for about 10-15 minutes and then slice and serve with a fresh salad.