Instant Pot Swedish Meatballs

Name: Instant Pot Swedish Meatballs
Ingredients: 1/2 stick (4 tablespoons) unsalted butter, at room temperature; 1/4 cup all-purpose flour; 1 1/2 cups low-sodium beef broth; 1 teaspoon Worcestershire sauce; Kosher salt and freshly ground black pepper; 1/4 cup heavy cream; 3/4 pound lean ground beef; 3/4 pound lean ground pork; 1 cup plain breadcrumbs; 1/4 cup grated yellow onion (from 1/2 large onion); 3 cloves garlic, grated; 2 large eggs, beaten; 1/4 teaspoon ground allspice; 1/4 teaspoon ground white pepper; Kosher salt; Vegetable oil, for browning; 1/4 cup fresh parsley leaves, chopped; Mashed potatoes or egg noodles, for serving