1. In a large mixing bowl, stir together the breadcrumbs and milk and let them sit for 1 minute so the crumbs can soften.

2. Add the ground turkey, egg, grated Parmesan, onion, garlic, parsley, salt, and black pepper to the bowl with the soaked breadcrumbs. Gently mix everything together with clean hands or a fork just until combined, being careful not to overwork the meat.

3. Scoop and roll the mixture into meatballs about 1 to 1 1/2 inches in diameter, placing them on a plate or parchment-lined tray as you go. Lightly oil your hands if the mixture feels sticky.

4. Heat the olive oil in a large skillet over medium to medium-high heat. Add the meatballs in a single layer without crowding the pan and brown them on all sides, turning gently with tongs, for about 6–8 minutes. Transfer the browned meatballs to a plate; they do not need to be fully cooked yet.

5. Reduce the heat to medium and add the butter to the same skillet. When melted, sprinkle in the flour and whisk it into the butter and pan drippings. Cook, whisking constantly, for 1–2 minutes until the roux smells nutty and turns light golden.

6. Slowly pour in the chicken or turkey broth while whisking, scraping up any browned bits from the bottom of the pan. Whisk in the Dijon mustard, Worcestershire sauce, and thyme or rosemary. Let the mixture simmer for 3–4 minutes, stirring often, until it begins to thicken.

7. Stir in the heavy cream or half-and-half and continue simmering for another 2–3 minutes, or until the gravy is smooth, creamy, and thick enough to coat the back of a spoon. Taste and season with additional salt and black pepper as needed.

8. Carefully nestle the browned turkey meatballs back into the skillet of gravy, turning them so they are well coated in the sauce. Cover the skillet and let the meatballs simmer gently for 10–12 minutes, or until they are cooked through and reach an internal temperature of 165°F (74°C).

9. Spoon extra gravy over the meatballs and garnish with a little extra chopped parsley or herbs. Serve hot over mashed potatoes, rice, pasta, or with your favorite sides.