Soak breadcrumbs in milk for a few minutes while you prep. This keeps the meatballs moist and juicy.
In a bowl, mix ground beef, onion, egg, salt, pepper, thyme, and the soaked breadcrumbs. Don’t overwork it—gentle hands win here.
Shape into small round meatballs about the size of a golf ball. If they look cute, that’s a win.
Heat butter and olive oil in a skillet over medium-high heat. Brown the meatballs on all sides, about 6–8 minutes. They’ll finish cooking later in the sauce, so don’t overcook now.
Remove meatballs briefly and set aside. Deglaze the pan with a splash of beef broth to lift all the tasty bits.
Stir in flour if you want a thicker sauce, then add the rest of the beef broth. Simmer until it starts to thicken, about 3–4 minutes.
Whisk in heavy cream, Dijon mustard, and allspice. Return meatballs to the pan and simmer gently for 6–8 minutes, until cooked through and glossy.
Taste and adjust salt or a pinch more pepper. If the sauce needs brightness, a tiny squeeze of lemon can help.How to Serve