Preheat the oven to 350 degrees F. Line a rimmed baking sheet with parchment paper.
Combine the meatloaf mix, mushrooms, breadcrumbs, provolone, parsley, eggs, onion, garlic, 1/4 cup of the ketchup, 1 tablespoon of the Worcestershire, 1 1/2 teaspoons salt and 1/2 teaspoon pepper in a large bowl. Using your hands, mix together until well combined.
Transfer the mixture to the prepared baking sheet and form it into a compact oval-shaped loaf, about 9 inches by 5 inches. Bake for 30 minutes.
Stir together the brown sugar, remaining 1/4 cup ketchup and remaining 1 teaspoon Worcestershire in a small bowl for the glaze. Remove the meatloaf from the oven and brush the top and sides all over with the glaze. Return to the oven and bake until the glaze starts to caramelize and a thermometer inserted in the center of the meatloaf registers 160 degrees F, about 25 minutes more. Let rest for 10 minutes before slicing and serving.
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