Preheat the oven to 400° and dig out your long lost loaf pan.
Combine the chopped onion, breadcrumbs, egg, Parmesan, mustard, parsley, and roasted red peppers in a bowl and season with a good teaspoon of salt and a few cranks of pepper.
Then mix in a handful of the ground beef to get things going before adding the rest of the beef.
Smush it into the loaf pan, and bake for 40-60 minutes, depending on your oven.
Let it rest for 10-15 minutes before serving, during which time you can make the glaze in the final 5 minutes: throw ingredients into a small saucepan and simmer until harmonious.
Slice the meatloaf, spooning glaze over as desired.
