1. Prepare the Meatballs

• In a large bowl, combine the ground beef, breadcrumbs, egg, milk, Worcestershire sauce, Dijon mustard, garlic powder, onion powder, salt, and black pepper.
• Mix gently with your hands until just combined—don’t overmix, or the meatballs may turn out tough.
• Roll the mixture into 1-inch meatballs (about 18–20 meatballs).

2. Brown the Meatballs

• Heat 1 tablespoon olive oil in a large skillet over medium-high heat.
• Add the meatballs in a single layer and cook for 3–4 minutes per side, until browned on all sides.
• Remove the meatballs from the pan and set aside.

3. Make the Gravy

• In the same skillet, melt 2 tablespoons butter over medium heat.
• Add the sliced onions and mushrooms and sauté for 5–6 minutes, until softened.
• Sprinkle in flour and stir constantly for 1 minute, allowing it to coat the onions and mushrooms.
• Slowly pour in beef broth, whisking to prevent lumps.
• Stir in Worcestershire sauce, Dijon mustard, salt, pepper, and thyme.
• Let the gravy simmer for 3–4 minutes, until slightly thickened.

4. Simmer the Meatballs in the Gravy

• Return the browned meatballs to the skillet, nestling them into the gravy.
• Reduce the heat to low and let them simmer for 10 minutes, stirring occasionally.
• The meatballs will absorb the flavor while the gravy thickens beautifully.

5. Serve and Enjoy!

• Spoon the meatballs and gravy over mashed potatoes, egg noodles, or rice.
• Garnish with fresh parsley for a pop of color and freshness.