Swedish Meatballs

Name: Swedish Meatballs
Ingredients: 1½ pounds lean ground beef or a combination of ¾ pound ground beef, ½ pound ground veal, and ¼ pound ground pork; 1 large egg; 1 cup fine breadcrumbs; ¼ cup minced fresh parsley; ½ teaspoon freshly grated nutmeg, or to taste; Pinch of ground allspice; Salt and pepper, to taste; 1 tablespoon canola oil, plus more if needed; 1 tablespoon butter, plus more if needed; 1 cup finely chopped onion; 3 tablespoons all-purpose flour; 1 cup warm nonfat, low-sodium beef broth; 1 cup warm nonfat, low-sodium chicken broth; 1 cup warm heavy cream