Preheat your oven to 375 degrees Fahrenheit.
In a medium bowl, mix together the minced onion, grated Cheddar cheese, and thawed frozen shredded hash browns.
Heat the olive oil in a large skillet over medium heat. Add the ground beef and cook until it is no longer pink. Add the pepper and salt and cook for an additional 3 minutes.
Grease a 9x13-inch baking dish with butter. Pour the ground beef mixture into the prepared baking dish and spread it out evenly. Sprinkle the cheese, onion, and hash brown mixture over the top of the ground beef.
On a lightly floured surface, roll out the refrigerated biscuit dough. Cut the dough into 6 equal size rounds. Place the rounds over the top of the ground beef mixture and press down gently to seal. Brush the tops of each round with melted butter.
Bake in preheated oven for 25-30 minutes, or until the dough is golden brown. Sprinkle garlic salt over the top of each round and serve warm.