Brown beef in a deep 12-inch saute pan over medium-high heat for 7 to 8 minutes, breaking it into small crumbles and cooking to 160°F. Spoon off excess fat and stir in garlic for 30 seconds.
Add orecchiette, broth, salt and pepper and bring to a simmer. Cook uncovered over medium-low heat for 13 to 16 minutes, stirring often to separate nested pieces, until tender; add reserved water if needed.
Simmer briefly if more than a shallow coating of broth remains. Stir in butter and cream and heat gently for 1 minute without a hard boil.
Remove the pan from the burner and wait 1 minute. Fold in Parmesan a small handful at a time until smooth, adding a little remaining reserve water if the coating becomes too tight.
Serve immediately in warm bowls while the cream sauce remains fluid.