01 - Preheat oven to 400°F. Line a baking sheet with parchment paper to prevent sticking and ensure even crisping.
02 - Melt butter with olive oil in a skillet over medium heat. Add sliced onions and cook, stirring occasionally, until golden and caramelized, about 8-10 minutes. Season with salt, pepper, garlic powder, and thyme during cooking.
03 - Lay tortillas flat on a clean surface. On each tortilla, layer sliced roast beef, caramelized onions, and one slice of provolone cheese evenly.
04 - Tightly roll up each tortilla starting from one end, creating a compact cylinder. Place seam-side down on the prepared baking sheet. Optionally brush tops with olive oil for enhanced crispiness.
05 - Bake for 10-12 minutes until tortillas achieve a golden-brown color and become crisp, and cheese is fully melted throughout.
06 - While roll ups bake, combine beef broth, Worcestershire sauce, soy sauce, onion powder, and garlic powder in a small saucepan. Bring to a simmer over medium heat and cook for 5-7 minutes to develop flavor. Adjust seasoning if needed.
07 - Remove roll ups from oven and allow to cool for 2-3 minutes. Slice each roll in half diagonally for easier handling. Serve immediately with warm au jus for dipping.