Ingredients

• 8–10 Servings
• Butter or cooking spray for casserole dish
• 6 large eggs
• 2½ cups whole milk
• 2 cups sliced green onions
• ½ cup heavy cream
• ½ cup finely grated Romano cheese
• 2 Tbsp. chopped fresh oregano
• ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt
• Freshly ground black pepper
• 2 Tbsp. extra-virgin olive oil
• 1 lb. hot Italian sausage, casings removed
• 1 large red bell pepper, halved, seeded, cut into ½" strips
• 1 1-lb. loaf rustic French bread, cut into ½" slices
• 2 cups (loosely packed) coarsely grated Fontina cheese, divided

Preparation

Step 1
Place rack in middle of oven; preheat oven to 350°. Coat a 13x9x2" ceramic or glass baking dish with butter or cooking spray. Whisk 6 large eggs, 2½ cups whole milk, 2 cups sliced green onions, ½ cup heavy cream, ½ cup finely grated Romano cheese, 2 Tbsp. chopped fresh oregano, and ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt in large bowl; add a generous amount of freshly ground black pepper. Set aside.
Step 2
Heat 2 Tbsp. extra-virgin olive oil in a large skillet, preferably nonstick, over medium-high. Add 1 lb. hot Italian sausage, casings removed; push sausage to one side. Add 1 large red bell pepper, halved, seeded, cut into ½" strips, to other side of skillet. Sauté over high heat, breaking up sausage with a wooden spoon, until sausage is cooked through and peppers are brown in spots, 6–8 minutes.
Step 3
Arrange half of one 1-lb. loaf rustic French bread, cut into ½" slices, in prepared baking dish. Pour half of egg mixture over. Sprinkle with 1 cup (loosely packed) coarsely grated Fontina cheese, then half the cooked sausage mixture. Repeat layering with remaining bread slices, remaining egg mixture, remaining 1 cup (loosely packed) coarsely grated Fontina cheese, and remaining sausage mixture. Let stand 20 minutes, occasionally pressing on bread to submerge. Bake breakfast casserole until puffed and edges are golden brown, about 1 hour. Cool slightly.
Do ahead: Breakfast casserole can be assembled 2 days ahead; refrigerate, tightly covered with aluminum foil. Breakfast casserole can be baked 1 day ahead; reheat in a 350° oven for 10–15 minutes or until warmed through.