For the meatloaf: Preheat the oven to 375 degrees F.
Combine the ground beef, milk, onion, garlic, Heinz 57, breadcrumbs, parsley, salt and pepper in a bowl. Mix well.
Form the ground beef mixture into a loaf and place in a baking dish. Bake until the meatloaf reaches an internal temperature of 150 degrees F, 45 to 60 minutes, basting with the pan drippings every 15 minutes. Brush the meatloaf with the BBQ sauce 15 minutes before it's done cooking.
Remove the meatloaf from the oven and allow it to rest for 15 minutes, then cut into six portions and hold for plating.
For the ham hock broth:
Fill a 6-quart pot with 1 gallon cold water. Add the ham hocks. Bring the water to a boil over high heat, then reduce to a simmer. Allow the broth to simmer for 3 hours. Add the onions, carrots, celery and corn cobs, and simmer for 1 hour more. Strain the broth through a fine-mesh sieve (the final quantity should be between 2 and 3 quarts). Remove the ham hocks and pick the meat for use in the collard greens.
For the collard greens: Melt the butter in a large pot. Add the onions and garlic, and saute for 3 to 4 minutes to sweat the onions. Add the chile flakes and saute 1 minute. Add the collard greens and ham hock meat, stirring to wilt the collards. Add the cider vinegar, apple juice and 8 cups of the ham hock broth, and bring to a simmer. Cover the pot and simmer until the greens are tender, 1 hour. Season with salt and pepper.
For the mac and cheese: In a saucepot, melt the butter and then whisk in the flour to make a roux. Cook the roux for 2 minutes, then slowly whisk in the milk and bring to a simmer. Cook for 10 to 15 minutes, whisking regularly.
Add the cream cheese and cheddar, stirring until all the cheese is melted into the sauce.
Just before plating, heat the chicken stock in a pan and add the cooked pasta. Once the pasta is hot, add the cheese sauce and bring to a boil. Reduce the sauce to a thick consistency that coats the back of the spoon. Stir in the salt and pepper.
For Plating: Divide the mac and cheese between the six plates. Place a piece of the meatloaf over the top of the mac and cheese. With a slotted spoon, put some of the collard greens next to the meatloaf. Serve.
Melt the butter in a saucepot. Add the onions and garlic, and saute until the onions are translucent. Add the chili powder, smoked paprika, dry mustard, garlic powder, onion powder and cayenne. Cook for 2 to 3 minutes to toast the spices. Add the brown sugar and molasses; stir until the sugar is dissolved.
Add the ketchup, Dijon mustard, Worcestershire sauce and cider vinegar, and bring to a simmer. Cook the sauce for 30 to 45 minutes and then puree with an immersion blender. Season with salt and pepper. Yield: 1 gallon