Preheat Oven: Preheat the oven to 400°F (200°C). Lightly grease a 9-inch (23cm) pie dish with cooking oil spray or butter.
Thaw Pastry: Remove the puff pastry from the freezer and place it on the bench to thaw according to the packet instructions while you prepare the filling.
Sauté Vegetables: Heat the olive oil or butter in a large skillet over medium-high heat. Add the diced onion and broccoli florets and cook, stirring occasionally, for 4 minutes. Add the minced garlic during the final minute and cook until fragrant. Remove from the heat and allow to cool slightly.
Whisk Eggs: In a large mixing bowl, whisk the eggs until combined.
Prepare Filling: Add the cream, salt and pepper and whisk until well combined.
Add Cheese & Vegetables: Stir the cheddar cheese and cooked broccoli mixture into the egg mixture until evenly distributed.
Line Pie Dish: Once the pastry is thawed, gently press it into the prepared pie dish, allowing it to come up the sides. If there is any excess overhanging, gently fold it back over itself to create a rustic edge.
Fill Pie Dish: Pour the filling into the pastry-lined pie dish and spread into an even layer.
Bake: Bake for 35-40 minutes, or until the centre is set with a slight jiggle and the top is lightly golden.
Cool and Serve: Allow the quiche to rest for 5 minutes before slicing. Enjoy!