Preheat oven to 375°F (190°C) and line a large baking sheet with parchment paper.
In a large skillet over medium-high heat, cook the ground beef and chopped onion until the beef is fully browned and the onion is translucent.
Drain the rendered fat from the skillet and return to the heat.
Season the beef with garlic powder, salt, and black pepper; stir to combine and remove from heat.
Allow the beef to cool for 5 minutes, then stir in the shredded cheddar cheese until evenly distributed.
Unroll the crescent dough and separate into 8 triangles along the perforated lines.
Place approximately 3 tablespoons of the beef and cheese mixture onto the wide end of each dough triangle.
Roll the dough towards the point, tucking in the edges to secure the filling, and place onto the prepared baking sheet with the point side down.
Brush the tops of the rolls with melted butter and sprinkle with dried parsley.
Bake for 12 to 15 minutes or until the pastry is golden brown and the cheese is melted.