Spinach Gratin

By mirelsonp

Recipe source: Cooks Country | December/January 2014
Note: Thaw frozen spinach in the refrigerator overnight. Before you use it, squeeze it as dry as you can using a dish towel.

Ingredients

• 2 slices hearty white sandwich bread, torn into 1-inch pieces
• 8 Tbsp unsalted butter
• 8 oz Gruyere cheese, shredded (2 cups)
• Salt and pepper
• 1 onion, chopped fine
• 4 garlic cloves, minced
• 1/8 tsp cayenne pepper
• 2 Tbsp all-purpose flour
• 4 cups half-and-half
• 8 oz curly-leaf spinach, stemmed and chopped coarse
• 1 Tbsp Dijon mustard
• 1/8 tsp ground nutmeg
• 2 1/2 lbs frozen whole-leaf spinach, thawed, squeezed dry, and chopped fine
• 1/2 cup minced fresh parsley
• 1 tsp grated lemon zest, plus lemon wedges for serving

Preparation

Step 1

1. Adjust oven rack to upper-middle position and heat oven to 425 degrees F. Pulse bread in food processor to fine crumbs, about 10 pulses; transfer to bowl. Melt 3 Tbsp butter in microwave, about 30 seconds. Stir melted butter, 1/2 cup Gruyere, 1/2 tsp salt, and 1/2 tsp pepper into crumbs; set aside.

2. Melt remaining 5 Tbsp butter in Dutch oven over medium heat. Add onion and cook until lightly browned, 7 to 9 minutes. Stir in garlic and cayenne and cook until fragrant, about 30 seconds. Stir in flour and cook for 1 minute. Slowly whisk in half-and-half and bring to simmer. Cook, whisking occasionally, until slightly thickened and reduced to about 3 1/2 cups, about 10 minutes.

3. Stir in curly-leaf spinach and cook until just wilted, about 0 seconds. Off heat, stir in mustard, nutmeg, 1 1/2 tsp salt, 1 tsp pepper, and remaining 1 1/2 cups Gruyere until cheese is melted. Stir in thawed frozen spinach until thoroughly combined. Season with salt and pepper to taste. Transfer mixture to buttered 13 x 19-inch baking dish.

4. Sprinkle crumb mixture evenly over spinach mixture. Bake until bubbling around edges and crumbs are golden brown, 15 to 17 minutes. Transfer to wire rack. Combine parsley and lemon zest in bowl; sprinkle over gratin. Let cool for 10 minutes. Serve with lemon wedges.

To Make Ahead: Crumb mixture can be covered and refrigerated for up to 24 hours. Spinach mixture can be cooked and refrigerated for up to 24 hours. When ready to serve, bake gratin until hot throughout, 15 to 20 minutes, then proceed with step 4.