Preheat oven to 400°F or 200°C and grease a 9 inch pie pan

Cook ground beef and onion for 6 to 8 minutes until browned, then drain excess grease

Spread the beef mixture evenly into the prepared pan

Sprinkle shredded cheddar cheese evenly over the meat

Whisk milk, onion soup mix, Bisquick, and eggs until smooth

Pour the batter evenly over the cheese layer

Bake for about 25 minutes until golden and set in the center

Let cool for a few minutes before slicing and serving