This spinach pie is made with eggs, caramelized onions, gruyere cheese, and golden puff pastry. An easy side dish idea for Thanksgiving or a family dinner!
Note: Let the puff pastry thaw in the fridge overnight. Don't unroll it frozen. Don't let it sit at room temperature for too long as it can affect it from rising.
Heat the onions for 15 minutes, decrease the heat to medium-low, and continue to cook until they’re brown and caramelized. This takes about 35 minutes total but is worth it for the flavor. Note: If time doesn’t allow for this, use one onion instead and soften for 7 minutes.
Drain the water from the spinach.
Brush the top of the casserole with the egg wash, don’t let it drip down the sides as that can affect rising.
Make Ahead Method:
Mix the filling ingredients up to 2 days ahead of time and store in an airtight container until ready to bake.
Proceed with assembling the casserole with the puff pastry and bake as instructed.