In a medium frying pan over medium-high heat, melt butter. Once melted add onions and worcestershire sauce. Stir and coat in melted butter. Reduce heat to medium-low and continue to let simmer while beef cooks, stirring occasionally.
Combine Spicy Mayo in a small bowl and set aside
In a large saute pan over medium high heat, add ground beef, onion powder, paprika, garlic, salt, pepper, and worcestershire sauce. Cook and crumble until no longer pink. Drain off excess fat.
Preheat Griddle to High (or 400degF, depending on setting options). Note - you can use a flat bottom pan on the stovetop if you do not have a griddle, you will just have to cook the sandwiches in batches.
Spread Miracle Whip on one side of each slice of bread. Build the sandwich with the mayo spead side down, add one and a half slices of swiss cheese, portion of ground meat, drizzle with spicy mayo, portion of onions, one and a half slices of cheddar cheese and slice of bread (mayo on top). Repeat with remaining sandwiches.
Place on hot griddle and cook for 3-4 minutes on each side. Serve hot!