Preheat your oven to 400°F (200°C). Grease a 9-inch pie plate and set aside.

In a skillet over medium heat, cook the ground beef and chopped onion together for 6-8 minutes, breaking up the meat as it cooks until the beef is browned and the onion is tender. Drain any excess fat thoroughly.

Stir in the salt, black pepper, Worcestershire sauce, and ketchup. Mix well and cook for 1 more minute, stirring constantly, until fragrant.

Transfer the beef mixture to the prepared pie plate and spread it evenly across the bottom. Sprinkle the shredded cheddar cheese over the beef in an even layer.

In a medium bowl, whisk together the milk, eggs, and Bisquick mix until smooth with no lumps, about 30-45 seconds. Pour this mixture evenly over the beef and cheese.

Bake for 25-30 minutes until the top turns golden brown and puffs up. The edges should pull slightly away from the pan. Insert a knife into the center - it should come out clean with no wet batter clinging to it.

Let the pie rest for 5 minutes before slicing and serving for the cleanest cuts.