6 demi baguettes (each about 8 inches long)
24 large eggs
1/2 teaspoon kosher salt
1 cup full-fat sour cream
12 ounces breakfast sausage, cooked and crumbled
3 cups shredded cheddar cheese, divided
6 scallions, green and white parts thinly sliced, divided
Arrange a rack in the middle of the oven and heat to 350°F.
Cut a deep-V into the top of each baguette. Remove the tops and the soft interior of the bread, leaving no more than a half-inch on the bottom and sides of the baguettes (save the tops and interior for another use); set aside.
Whisk together the eggs in a large bowl. Whisk in the sour cream and salt. Place the hollowed baguettes on a baking sheet. Use a brush to coat the outside of the bread with a thin layer of olive oil.
Divide the sausage between the baguettes. Sprinkle about half of the cheese over the sausage. Set aside 2 tablespoons of the scallions, then sprinkle the remaining scallions over the sausage and cheese.
Pour the egg mixture into each baguette, filling each not quite to the top. Be sure not to overfill the bread. You will not use all of the egg mixture at first. Allow the eggs to settle and soak into the bread, 1 to 2 minutes. Top off each baguette with more eggs as needed. Top each baguette with the remaining cheese and scallions.
Bake until the eggs are set and golden-brown, 30 to 35 minutes. Let the sandwiches cool on the baking sheet for about 5 minutes before cutting the loaves in half and serving.
Reheating: If not serving immediately, allow the egg boats to cool completely. Cut each baguette in half and wrap tightly in aluminum foil. Store in resealable bags in the refrigerator or freezer. Reheat uncovered in a 325°F regular or toaster oven until warmed through, about 20 minutes if refrigerated, or about 30 minutes if frozen.