Breakfast Macaroni and Cheese with Sausage and Hash Browns

Name: Breakfast Macaroni and Cheese with Sausage and Hash Browns
Ingredients: Kosher salt; 1 pound elbow macaroni; 1 tablespoon vegetable oil; 1 pound breakfast sausage, casings removed; 1 large yellow onion, chopped; 2 small green bell peppers, chopped; 2 1/2 cups half-and-half; 1/8 to 1/4 teaspoon cayenne pepper; 1 pound cream cheese, room temperature; 8 ounces sharp Cheddar, shredded (about 3 cups); 3 ounces Gruyere, shredded (about 1 cup); 1 1/2 cups frozen shredded hash browns, thawed; 4 tablespoons unsalted butter, melted