Preheat oven to 375°F. Line a cookie sheet with parchment paper or a silicone baking mat.
Unroll the pizza crust into a long rectangle. Cover with a layer of roast beef and a layer of cheese.
Roll up starting with the long side. Pinch the end to seal. Slice into equal size rolls and place on cookie sheet. Bake for 15-22 minutes, depending on size, until the dough is cooked through.
While the rolls are baking, make the au jus. Heat oil in a medium saucepan over medium heat. Add onion and cook about 3-4 minutes, until semi-translucent, then add the garlic and cook 1 minute more. Add the beef stock, Worcestershire, soy sauce, and bullion cubes, if using. Bring to a boil and cook for 4-5 minutes boiling (or until the bullion is dissolved). Taste carefully, and add salt and pepper as desired.
Serve hot rolls with the au jus.
Store in an airtight container in the refrigerator for up to 3 days.