• Step 1: In a large skillet or saucepan, melt the butter over medium heat. Add the chopped onion and minced garlic, and sauté for 3-5 minutes until the onion is translucent and the garlic is fragrant.
• Step 2: Sprinkle the all-purpose flour over the onion and garlic mixture, and stir to coat. Cook for 1-2 minutes, stirring constantly, to create a roux.
• Step 3: Gradually whisk in the beef broth, making sure to incorporate it smoothly and prevent any lumps from forming. Bring the mixture to a simmer and let it cook for 2-3 minutes, or until the sauce has thickened slightly.
• Step 4: Reduce the heat to low and stir in the sour cream, Dijon mustard, Worcestershire sauce, ground black pepper, and ground nutmeg. Taste and adjust the seasoning with salt as needed.
• Step 5: Add the frozen meatballs to the sauce and gently stir to coat them evenly. Cover the pan and simmer for 15-20 minutes, or until the meatballs are heated through and the sauce has reached the desired consistency.
• Step 6: Serve the Swedish meatballs with frozen meatballs hot, over a bed of mashed potatoes, egg noodles, or steamed rice. Garnish with chopped parsley, if desired.