• Preheat your oven to 375°F (190°C) and place the oven rack in the middle position. Lightly grease a baking dish or pan.
• In a large mixing bowl, gently combine all the meatloaf ingredients: ground meat, breadcrumbs, parsley, thyme, Worcestershire sauce, garlic, onion, beaten eggs, salt, pepper, milk, onion flakes, and Montreal steak seasoning. Be careful not to overmix, which can result in a tough texture.
• Form the mixture into an approximately 9-inch long by 5-inch wide loaf shape and transfer it to your prepared baking dish.
• Bake the meatloaf for 60 to 70 minutes, or until the internal temperature reaches 160°F (71°C) when checked with an instant-read thermometer inserted into the thickest part of the loaf. The meat should be well done with no traces of pink.
• Remove the meatloaf from the oven. Let it rest for at least 15-20 minutes before slicing. This is a crucial step to allow the juices to redistribute and ensure the meatloaf holds its shape. While it rests, prepare the gravy.

Brown Mushroom Gravy

• Scoop 6 tablespoons of the pan drippings from the baking dish into a large pan or skillet and heat over medium heat. Add the sliced mushrooms and sear them until they release their liquid and the liquid evaporates.
• Optional: Add the $1/2$ cup of dry white wine and cook for about 2 minutes on medium-high heat until the liquid reduces by about half. Reduce the heat back to medium.
• Add the flour to the mushrooms and cook, stirring constantly, for 1-2 minutes until the flour turns a light golden brown (a roux forms).
• Gradually whisk in the beef stock and add the thyme. Bring the mixture to a boil while whisking to fully incorporate the flour. Once boiling, lower the heat to a simmer and season with salt and pepper to taste. If the gravy is too thick, thin it with a little more stock or water; if it's too thin, raise the heat and reduce until satisfied.
• Slice the rested meatloaf and serve immediately with the warm mushroom brown gravy.