Before we get our hands dirty, preheat your oven to 350°F (175°C). This ensures that when your meatloaf hits the oven, it will cook evenly, resulting in a perfectly juicy loaf.

In a skillet, melt 2 tablespoons of unsalted butter over medium heat. Add the finely chopped onion, bell pepper, and mushrooms. Sauté them until softened, about 5-7 minutes. This will add depth and flavor to your meatloaf. Once they're perfectly softened, let them cool for a bit.

In a large mixing bowl, combine 2 pounds of lean ground beef, soy sauce, ketchup, and Dijon mustard. Crack in the 2 large eggs and sprinkle in 1 cup of seasoned panko breadcrumbs. Now introduce the sautéed vegetables.

Using your clean hands (or a fork, if you prefer), mix until everything is well combined. Don't overmix, though! Just enough to blend flavors.

Transfer your meat mixture to a greased baking dish or a lined baking sheet. Shape it into a loaf form, ensuring an even shape so it cooks uniformly.

Place slices of provolone cheese on top of the meatloaf. You can layer them neatly or make it a bit messy; I won’t judge!

Pop the meatloaf into your preheated oven and bake for about 60-75 minutes. It’s done when the internal temperature reaches 160°F (71°C). Keep an eye on it towards the end to avoid drying it out.

Once out of the oven, let your meatloaf rest for about 10-15 minutes. This allows the juices to redistribute.

Slice your creation and serve it warm. Pair it with your favorite sides for a truly unforgettable meal!