Steps
1. Preheat the oven to 375°F.
2. Grease a 9-inch round baking dish and line it with the puff pastry.
3. In a skillet, melt the butter and cook the onion until softened.
4. Add the broccoli and cook for a few minutes until the florets are tender.
5. Spread the mixture over the puff pastry and top with the grated cheese.
6. In a bowl, whisk together the eggs and milk. Season with salt and pepper.
7. Pour the egg mixture over the filling and bake for 25-30 minutes, or until golden brown.
8. Serve warm.