In a large skillet, heat the olive oil over medium heat. Add the diced onion and sauté for about 3-4 minutes until it becomes translucent.
Add the minced garlic and cook for an additional 1 minute until fragrant.
Increase the heat to medium-high and add the ground beef to the skillet. Cook, breaking it apart with a spatula, until browned and cooked through, about 5-7 minutes. Drain excess fat if necessary.
Stir in the halved Brussels sprouts, salt, black pepper, smoked paprika, soy sauce, Worcestershire sauce, and beef broth.
Cover the skillet and reduce the heat to medium. Cook for about 8-10 minutes, stirring occasionally, until the Brussels sprouts are tender.
If using, add the red pepper flakes for a bit of heat and stir to combine. Cook for an additional 1-2 minutes.
Remove from heat and serve warm.