Make the meatloaves:
Melt the butter in a 12-inch skillet over medium-high heat. Add the breadcrumbs and toast, stirring constantly, until deeply browned, about 3 minutes. Transfer to a large bowl to cool. Wipe the skillet clean.
In the skillet, combine the onion, oil, and 2 tsp. salt. Cook over medium heat, stirring frequently with a wooden spoon, until the onion is soft and just starting to brown, 4 to 5 minutes. Stir in the ginger and cook, stirring constantly, until fragrant, about 30 seconds. Add the green bell pepper and garlic and cook until the garlic is fragrant, about 1 minute. Stir in the coriander, cumin, and cracked pepper and cook, stirring and scraping the bottom of the skillet for 1 minute to diffuse the spices.
Add the mushrooms and cook, stirring often, until they release their liquid and the liquid has evaporated, 6 to 8 minutes. Stir in the cayenne and cook for 30 seconds. Stir in the garam masala, turn off the heat, and set aside to cool.
Position a rack in the center of the oven and heat the oven to 300°F. Add the beef, pork, turkey, red bell pepper, cilantro, eggs, ketchup, Parmigiano, and paprika to the bowl with the breadcrumbs and knead gently until everything is incorporated. Add the cooled mushroom mixture and knead gently until combined. Divide the mixture in half. On a parchment-lined rimmed baking sheet, mold the meat into two 9x5-inch loaves and bake for 1 hour.
Make the glaze:
While the meatloaves bake, whisk the glaze ingredients in a small bowl. After 1 hour of baking, remove the meatloaves from the oven. Evenly brush the glaze over each meatloaf and continue to bake until an instant-read thermometer reads 165°F when inserted into the center of a meatloaf, 30 to 40 minutes more. Let the meatloaves cool for 15 minutes before moving to a platter or cutting board with a large spatula (leave the juices and fat behind). Slice and serve.
To freeze, shape a loaf on its own parchment-lined rimmed baking sheet. Cover loosely with plastic and freeze until firm. Wrap in the parchment and then wrap tightly in foil. It will keep for 1 month. To bake, unwrap the frozen loaf, transfer to a rimmed baking sheet lined with fresh parchment, and thaw completely overnight in the refrigerator. Bake as directed.