Crush Chedz finely to get about 2 teaspons of Chedz crumbs (more or less on preference) using a rolling pin, food processor or Magic Bullet.
Place eggs in a saucepan, and cover with cold water. Bring water to a boil and immediately remove from heat. Cover, and let eggs stand in hot water for 20 minutes. Remove from hot water, and cool. To cool more quickly, rinse eggs under cold running water.
Pop out (remove) the egg yolks to a small bowl and mash with a fork. Add mayonnaise, mustard powder, vinegar, salt and pepper and mix thoroughly.
Fill the empty egg white shells with the yoke mixture and sprinkle each shell with Chedz crumbs (if serving immediately).
Cover lightly with plastic wrap and refrigerate for up to one day before serving. If not serving right away, do not sprinkle Chedz crumbs on top as it gets soft in the refrigerator (which is ok if you do not prefer the crunchiness). Sprinkle Chedz right before serving.
Crumble Chedz into crumbs using a food processor or rolling pin.
Whisk eggs, milk, salt, and ground black pepper in a large bowl. Add Chedz crumbs and stir until combined.
Mix ground beef and chopped onions in the Chedz mixture and transfer mixture into a 9x5-inch loaf pan, mini bread loaf pan or slow cooker.
To make the sauce (optional): Combine brown sugar, ketchup, mustard, Worcestershire sauce in a small bowl; spread over meat mixture.
-For 9x5-inch loaf pan: Bake in the preheated oven until no longer pink in the center, 1 to 1 1/4 hours. A thermometer inserted into the center should read at least 160 degrees F (70 degrees C).
-For mini bread loaf pan or regular sized cupcake pan: Bake for ~35 minutes.
-For slow cooker, cook on low for ~5-6 hours.