Place peppers on the grate directly over the top of the gas flame or in a grill pan over high heat. Let it roast for 20-25 minutes. Use a pair of tongs to give the pepper a quarter turn every 4-5 minutes until charred all over.
Seal charred peppers in a large ziploc bag for 15 minutes to steam the peels off. When cool enough to handle, remove the stem from each pepper and cut them in quarters. Remove the peels and seeds and dice the peppers. Place in a large bowl.
Preheat oven to 350°.
Pulse mushrooms in a food processor about 10 times until finely chopped.
Heat a large nonstick skillet over medium-high heat. Add oil to pan; swirl to coat. Add mushrooms to pan; sauté 15 minutes or until liquid evaporates, stirring occasionally. Add mushrooms to peppers. Wipe pan with paper towels. broccoli and onion to pan; sauté 6 minutes or until just tender, stirring occasionally. Add onion mixture to mushroom mixture.
Add breadcrumbs and the next 10 ingredients (through eggs) to mushroom mixture, stirring well. Spoon mixture into a 9 x 5-inch loaf pan coated with cooking spray; press gently to pack.
To prepare topping, combine 2 tablespoons ketchup and remaining ingredients in a small bowl; brush ketchup mixture over meat loaf.
Bake at 350° for 45 minutes or until a thermometer registers 155°. Allow to rest in the pan for 15 minutes before slicing.