Move an oven rack to the highest position in your oven, and preheat the broiler. Cover a sheet pan with foil and grease lightly. Take the wrapper off the package of ground chuck and season the top side of the ground meat generously with salt, pepper, onion powder, and garlic powder. Flip the meat over and season that side, too. With wet hands and a light touch, form the beef into golf ball-sized meatballs, handling them only enough to form nice spheres. Put the meatballs on the sheet pan not touching each other. Run the meatballs under the hot broiler for 7 or 8 minutes. Remove from the oven and set aside.
Meanwhile, melt the butter in a Dutch oven and add the mushrooms and a pinch of salt. Sauté the mushrooms until they’re limp and then add the flour. Stir for a minute or two. Add the tomato paste. Cook, stirring, for another minute or two as the raw taste cooks off. Add the wine and cook, stirring and scraping the bottom of the pan clean, for 2 or 3 minutes. Stir in the beef stock, the Herbes de Provence, ½ t. each salt and ground pepper. Bring the sauce to a simmer, turn the heat to low and add the meatballs.
Cook uncovered for about 15 minutes. If you want a thicker sauce--and I always do--stir together 2 T. of cornstarch and 2 T. cold tap water in a small bowl. Stir this slurry into the meatballs and sauce and turn the heat to medium. Taste for salt and pepper and adjust if needed. When the sauce begins to bubble it will thicken quickly. As soon as it’s thick, turn the heat off and serve.