Dice all peppers and onion into small, even pieces.
Cook peppers and onion in oil over medium-high heat for 7–8 minutes until tender. Set aside.
In the same pan, cook ground beef with salt and pepper until browned. Drain excess fat.
Add veggies back in with cream cheese, ketchup, Worcestershire, garlic powder, water, and seasoning. Cook until thick and creamy.
Turn off heat. Add shredded cheese, let sit, then stir until melted and gooey.
Toast buns in a dry skillet or under the broiler until crisp.
Spoon filling onto buns, top with extra cheese if desired, and serve warm.