Spread softened butter on the inside of the hoagie rolls. Place them cut-side down in a large skillet over medium heat and toast until golden brown, about 1-2 minutes. Remove and set aside.

In the same skillet, heat 1 tbsp of olive oil. Add the sliced onion and bell pepper and cook, stirring occasionally, until softened and lightly browned (6-8 minutes). Add the minced garlic and cook for 1 more minute until fragrant. Remove vegetables from the skillet.

Add the ground beef to the skillet. Use a spatula to break it apart and cook over medium-high heat until fully browned, about 5-7 minutes. Drain any excess grease from the skillet.

Return the cooked vegetables to the skillet with the beef. Stir in the Worcestershire sauce, salt, black pepper, and garlic powder. Mix until everything is well combined.

Using your spatula, divide the mixture into four equal portions within the skillet. Place two slices of provolone cheese over each portion. Cover the skillet for 1-2 minutes to allow the cheese to melt.

Carefully transfer each cheesy beef portion into a toasted hoagie roll. Serve immediately.