Preheat oven to 375°F. Cook pasta in generously salted water according to package directions in a large pot, adding broccoli during final 2 minutes cook time. Drain; return pasta and broccoli to pot. Cook sausage in a large ovenproof skillet over medium-high, stirring often and breaking up sausage with a wooden spoon, until cooked through and no longer pink, about 10 minutes. Add sausage, marinara sauce, cream cheese, and salt to pasta mixture in pot; stir to combine. Return mixture to skillet; sprinkle with cheese. Bake until golden and bubbly, 15 to 18 minutes.