Step 1

Heat 1 tablespoon of the olive oil in a 12-inch nonstick skillet over medium heat until shimmering. Add 1 finely diced small yellow onion and 2 minced garlic cloves. Cook, stirring occasionally, until softened, 2 to 3 minutes. Transfer to a large bowl.

Step 2

Stir in 3/4 cup panko breadcrumbs, 1/4 cup whole milk, 1 large egg, 1 1/2 teaspoons kosher salt, 1/4 teaspoon ground nutmeg, 1/4 teaspoon ground allspice, and 1/4 teaspoon black pepper until combined.

Step 3

Add 12 ounces lean ground beef and 12 ounces ground pork and mix until evenly combined; do not overmix or the meatballs will be tough. Scoop out the mixture in 2-tablespoon portions (about and roll each between damp hands until a smooth ball forms. Place on a baking sheet.

Step 4

Heat the remaining 2 tablespoons olive oil in the same skillet (no need to clean) over medium heat until shimmering. Add half of the meatballs in a single layer and cook until browned on the bottom, about 2 minutes. Flip the meatballs and cook until browned on the other side, about 2 minutes more. Return to the baking sheet (the meatballs will not be cooked through). Repeat cooking the remaining meatballs and adding them to the baking sheet.

Step 5

Reduce the heat to medium-low and melt 3 tablespoons unsalted butter in the same skillet (no need to clean). Add 1/4 cup all-purpose flour and cook, stirring regularly, for 1 minute to cook the floury taste out. Gradually whisk in 2 cups low-sodium beef broth, 2 teaspoons Dijon mustard, 1/2 teaspoon kosher salt, and 1/4 teaspoon black pepper until smooth; scrape up any browned bits from the bottom of the pan. Bring to a gentle simmer.

Step 6

Return the meatballs in a single layer to the pan along with any accumulated juices. Simmer uncovered, stirring occasionally, until the meatballs are cooked through and the gravy is thickened, 10 to 12 minutes.

Step 7

Stir in 1/2 cup heavy cream. Taste the gravy and season with kosher salt and black pepper as needed. Serve the meatballs and gravy over cooked egg noodles or mashed potatoes and garnish with chopped fresh parsley leaves if desired.