Preheat the oven to 400ºF. Spray a 9" round deep dish pie plate or cake pan with cooking spray.
Using a skillet over medium heat, brown the ground beef and the onions together until the beef is no longer pink and the onions are translucent. Drain off any fat.
Add in the minced garlic, salt and pepper. Mix well.
Spread the beef mixture on the bottom of the prepared pie plate. Sprinkle the shredded cheese on top.
In a small bowl, whisk together the Bisquick, milk and eggs.
Pour evenly over the beef and cheese.
Bake for 30 minutes or until the middle of the pie is set and the top is golden brown. A knife inserted in the center should come out clean and feel hot. Serve immediately.