Cook noodles according to package directions. Drain and set aside.
In a large skillet over medium heat, cook the ground beef until browned. Drain excess fat.
Add garlic and ginger to the skillet. Stir and cook for 1–2 minutes.
In a bowl, whisk together soy sauce, beef broth, brown sugar, hoisin sauce, and cornstarch mixture.
Pour sauce into the skillet with beef. Simmer for 5–7 minutes until thickened.
Add cooked noodles and sesame oil. Toss to coat evenly.
Serve hot, garnished with green onions and red pepper flakes if desired.