Preheat your oven to 350°F. In a medium bowl, gently combine the ground beef, panko, parsley, allspice, nutmeg, minced onion, garlic powder, pepper, salt, and beaten egg. Mix with your hands just until everything comes together — overworking will make the meatballs tough.
Shape the mixture into 12 generous meatballs or 20 smaller ones, rolling them lightly between your palms. Keep them uniform in size so they cook evenly.
Heat the olive oil and 1 tablespoon of butter in a large skillet over medium-high heat. When the butter stops foaming, add the meatballs and brown them on all sides, turning carefully with tongs. You want a rich golden crust all around — this adds serious flavor to the final dish.
Transfer the browned meatballs to a rimmed baking sheet and slide into the 350°F oven. Bake until they're cooked through with no trace of pink in the center — this usually takes about 15-20 minutes depending on size.
While the meatballs finish cooking, add the remaining 4 tablespoons of butter to the same skillet. Once melted, whisk in the flour and cook until the mixture turns golden brown and smells nutty — about 2-3 minutes. This is your roux, and browning it properly gives the sauce depth.
Gradually pour in the beef broth, whisking constantly to prevent lumps. Follow with the heavy cream, Worcestershire sauce, and Dijon mustard, whisking everything smooth.
Bring the sauce to a gentle simmer and let it bubble until it coats the back of a spoon — usually 3-4 minutes. Taste and adjust with salt and pepper as needed. The sauce should be rich and velvety.
Nestle the cooked meatballs back into the creamy sauce and let them simmer together for a minute or two. This final step marries the flavors beautifully.
⏱ 1 min 30 sec
Serve immediately over buttered egg noodles or fluffy rice, spooning extra sauce over everything. A sprinkle of fresh parsley makes it picture-perfect.