Preheat the oven to 350°F.
In a bowl, break the bread up into small breadcrumbs with your hands. Add the buttermilk and heavy cream and mash into a paste. Let sit while you prepare the rest of the meatloaf.
In a mixing bowl, combine the parsley, garlic, Dijon, eggs, beef, pork, salt, pepper, onion, and Worcestershire sauce. Fold in the bread mixture until just combined.
Combine all of the meatloaf glaze ingredients in a small bowl.
Shape the meatloaf into a loaf pan or into a loaf shape in a 9x13 inch baking dish. Brush the glaze on top, saving some for serving. Bake for 45 minutes to 1 hour, until cooked through.
In a large stockpot, place the potatoes and a generous pinch of salt. Cover with cold water and bring to a simmer. Cook at a simmer until the potatoes are fork-tender, about 15 minutes. Drain the potatoes and return to the pot. Add the butter, milk, buttermilk, salt and pepper. Mash until smooth. Season with salt and pepper to taste.
Bring a large pot of salted water to a boil. When it boils, submerge the broccoli all at once for one minute, until bright green and crisp-tender. Immediately remove from the water with a strainer and run under cold water.
To serve, divide the mashed potatoes between plates. Top with slices of meatloaf and blanched broccoli.