Preheat oven to 375 degrees Fahrenheit (190 degrees Celsius).
In a large skillet over medium-high heat, brown the ground beef and onion until the beef is no longer pink. Drain excess grease.
Stir in the garlic powder, salt, black pepper, ketchup, and mustard until well combined. Remove from heat.
Unroll the crescent roll dough and separate into individual triangles.
Place approximately 2 tablespoons of the beef mixture and 1 tablespoon of shredded cheese on the wide end of each dough triangle.
Roll the dough from the wide end toward the point, tucking in the sides to enclose the filling.
Arrange the stuffed rolls in a 9x13 inch baking dish coated with non-stick spray.
Sprinkle the remaining cheese over the top of the rolls.
Bake for 12 to 15 minutes, or until the crescent rolls are golden brown and the cheese is melted.
Let stand for 5 minutes before serving.