Adjust oven rack to upper-middle position and heat oven to 500 degrees.
Cook bacon in large nonstick skillet over medium-high heat until almost done, about 3 minutes. Add onion and garlic and cook until softened, about 3 more minutes. Add broth, cream, pasta and 1/2 teaspoon salt; cover, and bring to boil. Once boiling, reduce heat to medium-low and simmer, stirring frequently, until pasta is tender, about 15 minutes.
Off heat, stir in Parmesan and season with salt and pepper. Transfer to 2-quart greased casserole dish and sprinkle with shredded cheese.
Bake until cheese is melted and spotty brown, about 5 minutes. Serve.