A cheesy masterpiece with loads of spinach, like mac n' cheese but without the noodles! Perfectly baked with a crunchy panko topping, this dish is a standout side for Thanksgiving.
1: Preheat the oven to 375°F.
2: In a dutch oven or large pot over medium-high heat, cook the onions with the butter until translucent and tender (8-10 minutes).
3: Add the flour to the sautéed onions and stir together for one minute.
4: Pour in 3 cups of warm milk and turn the heat down to medium-low.
5: Add the salt, pepper, and nutmeg. Stir to incorporate.
6: Turn off the heat and add the mozzarella cheese. Stir until melted completely.
7: Add the thawed and drained spinach into the cheese sauce and stir to combine.
8: Pour spinach gratin into a greased 8x8 (or 9x9) baking dish.
9: In a medium bowl, mix the melted butter, panko, salt, garlic, and parsley until the panko is coated.
10: Sprinkle the panko topping across the spinach gratin dish.
11: Bake at 375°F for 30 minutes, until panko is golden brown and gratin is bubbly.
12: If making in advance, cool completely, cover with foil, and refrigerate. Remove from fridge 1 hour prior to cooking, then warm at 300°F for 45-60 minutes covered.
