We turned the classic sandwich into a cheesy, meaty dip.
In a medium bowl, mix the roast beef, 1 tbsp. Worcestershire, and the garlic. In a large skillet, heat the oil over medium-high. Add the onion and a third of the sliced green bell peppers and cook, stirring often, until the onion begins to brown, about 3 minutes. Add the roast beef and cook, stirring often, until browned, about 2 minutes. Set aside 1/2 cup of the roast beef. Add the stock and Velveeta to the skillet. Reduce heat to medium and cook, stirring often, until the Velveeta is just melted, 2 to 3 minutes. Stir in the remaining 1 tbsp. Worcestershire and the garlic powder.
Garnish the dip with the reserved roast beef and the chopped green and red bell peppers. Serve the dip directly from the skillet with toasted baguette slices and the remaining sliced green, red, and yellow bell peppers.