Rosemary Baked Onions with Alfredo Sauce

Name: Rosemary Baked Onions with Alfredo Sauce
Ingredients: 4 medium sized Vidalia onions, trimmed and peeled; 4 1/2 tablespoons unsalted butter; rosemary sprigs; olive oil; 1 cup heavy cream; 1 1/2 teaspoons fresh garlic, minced; 1/2 cup parmesan-reggiano, grated; 2 tablespoons chives, minced; 2 teaspoons rosemary, minced; kosher salt and fresh ground pepper