Spinach and Fontina Casserole - Lidia

Ingredients

• Unsalted butter, for the baking dish
• Panko bread crumbs, for the baking dish
• 1-pound bag frozen spinach, thawed
• 8 large eggs
• 2 cups half-and-half
• Kosher salt
• Freshly ground black pepper
• 1 bunch scallions, chopped, green parts included
• 1 cup frozen peas, thawed
• 1/2 cup freshly grated Grana Padano
• 6 cups day-old crustless bread cubes
• 1 cup freshly grated Italian fontina