Begin by preheating your oven to 350°F (175°C). While the oven warms up, prepare a baking sheet lined with parchment paper or lightly grease a casserole dish to keep the meatloaf from sticking during baking.
In a large bowl, mix together the ground beef, breadcrumbs, finely chopped onion, minced garlic, beaten eggs, ketchup, Worcestershire sauce, thyme, and oregano. Season well with salt and freshly ground black pepper. Gently combine all ingredients with your hands until just mixed—avoid overmixing to maintain a tender texture.
Form the meat mixture into a loaf shape and carefully transfer it to your prepared baking dish. Place it in the preheated oven and bake for 50 to 60 minutes, or until the internal temperature reaches 160°F (71°C) when checked with a meat thermometer.
As the meatloaf bakes, prepare the mushroom gravy. In a skillet over medium heat, melt the butter and add the sliced mushrooms. Sauté them until they become golden brown and aromatic, which should take about 5 to 7 minutes.
Sprinkle the flour evenly over the mushrooms and stir continuously for about 2 minutes to cook off the raw flour taste. Slowly whisk in the beef broth, then stir in the heavy cream. Continue stirring until the gravy thickens into a smooth, rich consistency—this should take another 5 to 7 minutes. Season with salt and pepper to your liking.
Once the meatloaf is done, allow it to rest for a few minutes before slicing. Serve thick slices with a generous spoonful of warm mushroom gravy over the top, and enjoy the comfort of a classic homemade dish.