I like meatloaf and have been working on this recipe for some time; I think I've got it pretty close. This is not a simple, easy, and inexpensive meatloaf like many are, but it sure is tasty. Be careful, my times are based on glass bread pans; don't overcook the meat if you are using tin.
Mix ground beef, sweet potato, onion, and oats in a large mixing bowl.
Beat eggs, salt, thyme, and pepper together in a small bowl. Add 3/4 cup ketchup, vegetable juice, Worcestershire sauce, 1 tablespoon prepared mustard, and mustard powder to the egg mixture; stir. Pour the egg mixture into the large mixing bowl; use your hands to mix together. Cover bowl with plastic wrap and refrigerate 8 hours to overnight.
Preheat oven to 350 degrees F (175 degrees C). Grease 2 8 1/2x4x3-inch glass bread pans.
Divide meatloaf mixture into prepared bread pans.
Bake meat loaves on center rack in preheated oven for 1 hour.
Stir 3/4 cup ketchup, brown sugar, and 1 teaspoon prepared mustard together in a bowl; spread over the meatloaf.
Divide ketchup mixture and spread over the loaves; continue baking for 15 minutes.