Preheat oven to 350 degrees F / 177 degrees C.
Place ground beef in a skillet over medium-high heat. Add garlic, onion, burger seasoning, and salt and pepper to taste. Using a spatula, break the ground beef into chunks.
Add Worcestershire sauce and cream cheese. Cook until ground beef is no longer pink and cream cheese has melted.
Remove skillet from heat.
In a medium bowl, combine eggs, ½ cup / 118.3 mL of the shredded cheddar cheese, ½ cup / 118.3 mL of the shredded white cheddar cheese, heavy cream, and mustard.
Oil an 8 x 11-inch baking dish with oil or cooking spray. Pour the ground beef mixture into the dish.
Drizzle the egg and cheese on top. Combine.
Sprinkle the remaining ½ cup / 118.3 mL shredded cheddar and ½ cup / 118.3 mL shredded white cheddar cheese on top.
Bake for 15 to 20 minutes or until the cheese begins to bubble.
Cool before serving.
