Bisquick mix: a premade baking mix that typically contains flour, baking powder, salt, and other ingredients
Milk: for the biscuit layer
Egg: to bind the Bisquick layer
Ground beef: any lean ground beef
Sweet onion: for a mild and slightly sweet flavor
Green bell peppers: a mild pepper often featured in Philly cheesesteaks and steak sandwiches
Brown gravy mix: dry mix to flavor the ground beef
Slices of provolone cheese: Philly cheesesteaks are typically made with American cheese, provolone cheese, or Cheez Whiz
Preheat your oven to 375°F (190°C).
Grease a 9×13-inch casserole dish with cooking spray and set aside.
In a mixing bowl, add the Bisquick, milk, egg, and half of the black pepper.
Combine until the batter is smooth.
Pour the Bisquick mixture into the prepared baking dish.
In a large skillet over medium-high heat, brown the ground beef, about 5-7 minutes.
Add the onion slices and green bell pepper slices to the skillet with the beef and cook until softened, about 5-7 minutes. Drain any excess grease.
Stir the brown gravy mix, water, and the remaining black pepper into the ground beef mixture. Simmer for about 3-5 minutes until the liquid is reduced.
Spread the beef mixture over the Bisquick.
Top with the cheese slices, spacing evenly and tearing the slices as needed for full coverage.
Bake the casserole in the preheated oven for 25-30 minutes, or until the layer of provolone cheese is golden brown and a toothpick inserted in the biscuit layer comes out clean.