Potato, Sausage, and Spinach Breakfast Casserole

 Yield: 8-10 servings

Active Time:  40 minutes    Total Time:  1 hour 20 minutes

16 large eggs

1 1/4 cups heavy cream

1 1/2 tsp kosher salt plus more

3/4 tsp freshly ground black pepper plus more

5 Tbsp unsalted butter, divided

12 oz fresh breakfast sausage links

2 cups sliced leeks, white ad pale-green parts only

2 russet potatoes (1 1/2 lb), peeled, shredded, lightly squeezed

1 lb frozen spinach, thawed, squeezed dry, roughly chopped

1 1/2 cups (4 oz) grated Gruyere cheese

1/2 cup (1 1/2 oz) grated Parmesan

Position a rack in top third of oven; preheat to 350 degrees.  Whisk eggs, cream, 1 1/2 tsp salt, and 3/4 tsp pepper in a large bowl; set aside.

Melt 1 Tbsp butter in a 12 inch cast iron or nonstick ovenproof skillet over medium heat.  Add sausages and cook, turning often, until browned all over, about 10 minutes.  Transfer to a plate.  Add leeks to skillet.  Season with salt; cook until wilted, about 5 minutes.  Transfer to a small bowl.

Melt 2 Tbsp butter in same skillet over medium heat.  Add potatoes, spreading out in an even layer.  Cook without stirring until bottom and edges are crisp and golden brown, about 10 minutes.  Slide potato pancake onto a large plate.  Invert onto another large plate. Melt 1 Tbsp butter in skillet.  Slide potato pancake into skillet, browned side up; cook until bottom is golden brown, about 10 minutes.

Scatter spinach, leeks, and sausages over potato pancake, each in an even layer.  Season with salt and pepper, then pour in egg mixture.  Sprinkle both cheese over.

Bake until casserole is puffed and golden brown 35-40 minutes.  Serve warm or at room temperature.