Pancetta Wrapped Pork Roast

Name: Pancetta-Wrapped Pork Roast
Ingredients: 1 pork loin (1 1/2 pounds); 8 to 10 cipollini, or small white onions, unpeeled; 1 tablespoon extra-virgin olive oil; Coarse salt and freshly ground pepper; 2 tablespoons finely chopped fresh rosemary, plus several sprigs; 1/4 pound pancetta (Italian bacon), or bacon, thinly sliced; 1 teaspoon unsalted butter, softened; 1 teaspoon all-purpose flour; 1 cup chicken stock, preferably homemade; 1 teaspoon all purpose flour