Preheat oven to 400 degrees.
Over medium-high heat, saute onions and peppers in butter until crisp tender. You want them to have a nice bright color still.
Add sliced roast beef to sauteed onions and peppers. Stir together.
Add Worcestershire sauce, hot sauce and garlic powder. Stir to distribute.
Layer tortilla chips on an oven safe plate. Sprinkle a little bit of the cheese over chips.
Next, evenly layer the beef, onion and pepper mixture over the cheese layer.
Finish with layer of remaining cheese.
Bake the nachos for 3-5 minutes or until the cheese is melted and the nachos look amazing!
Serve with sour cream if desired.